Cbselearn: Std 10 Chapter 1,2,3,4 important questions

MCQ s 1 MARK EACH

1. Which of the following is correct observation of the reaction shown in the following set up?

a. Brown powder of Magnesium oxide is formed

b. Colourless gas which turns lime water milky is evolved

c. Magnesium ribbon burns with brilliant white light

d. Reddish brown gas with a smell of burning Sulphur has evolved.

2. The following reaction is used for the preparation of oxygen gas in the laboratory

heat

2KClO3 (s) ---------------→ 2KCl (s) + 3O2 (g)

Catalyst

Which of the following statement is/are correct about correct about the reaction?

a. It is a decomposition reaction and endothermic in nature

b. It is a combination reaction

c. It is a decomposition reaction and accompanied by release of heat

d. It is a photochemical decomposition reaction and exothermic in nature

3. Which of the following is not a physical change?

a. Boiling of water to give water vapour

b. Melting of ice to give water

c. Dissolution of salt in water

d. Combustion of Liquified Petroleum Gas (LPG)

4. A powdered salt (X) in a dry test tube was heated that evolves brown fumes of nitrogen

dioxide and a yellow residue of lead oxide is also formed. The salt (X) is

a. MgCO3

b. Pb (NO3)2

c. (NH4)2SO4

d. CaCO3

5. Solid Calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by

liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in

water to form its solution called lime water. Which among the following is (are) true about

slaking of lime and the solution formed?

i. It is an endothermic reaction

ii. It is an exothermic reaction

iii. The pH of the resulting solution will be more than 7

iv. The pH of the resulting solution will be less than 7

a. i. and ii

b. ii and iii

c. i and iv

d. iii and iv

6. A person added aluminium metal to colourless solution of zinc sulphate. After half an hour,

the solution was observed. It was colourless. She recorded her observations in the following

statements:

i. No reaction occurred

ii. Reaction occurred and aluminium sulphate was formed

iii. Zinc is more reactive than aluminium

iv. Aluminium is more reactive than zinc

The correct observations are:

a. i and ii

b. ii and iii

c. iii and iv

d. ii and iv

7. Directions: (Q. No.’s 7-10) In each of the following questions, a statement of Assertions is

given by the corresponding statement of Reason. Of the statements mark the correct

answer as:

a. Both Assertion and Reasons are true and reason is the correct explanation of

Assertion.

b. Both Assertions and Reasons are true, but Reason is not the correct explanation of

Assertion.

c. Assertion is true, but Reason is false

d. Assertion is false, but Reason is true

Assertion:In the following chemical equation,

CuO(s) + Zn(s) →ZnO(s) + Cu(s)

Zinc is getting oxidized and copper oxide is getting reduced

Reason: The process in which oxygen is added to a substance is called oxidation whereas

the process in which oxygen is removed from a substance is called reduction.

8. Assertion: Photosynthesis is considered as an endothermic reaction

Reason: Energy gets released in the process of photosynthesis

9. Assertions: On adding a solution of Sodium sulphate to the solution of Barium Chloride,

Barium sulphate and Sodium Chloride are formed as products.

Reason: Such kind of reactions are called Decomposition reaction.

10. Assertion: When copper oxide is added to dilute hydrochloric acid, the colour of the

solution becomes blue-green

Reason: Blue-green colour of the solution is due to the formation of copper (II)chloride

11. Endothermic reaction requires energy in the form of

a.heat

b.light

c. Electric

d.All of these

12. Write Some characteristics of chemical reaction

a. Change in colour

b. Change in temperature

c. Evolution of gas & formation of ppt

d. All of these

13. C6H12O6 + 6O2—-------------------------6CO2 + 6 H2O

The above reaction is a /an

a. Displacement reaction b . Endothermic reaction

b. C. Exothermic reaction d. Neutralization reac6

14. A teacher gave two test tubes to the Students

One contains water and the other contains NaOH.She asked them to identify the test tube

containing NaOH solution. Which one of the can be used for identifying

a. Blue litmus 3

b. Red litmus

c. Sodium carbonate solution

Dilute HCl

15. In rusting of iron the reddish brown coating formed on iron is

a.FeO

b.Fe3O4

c.Fe2O3

d.FeO2

16. Respiration is an —---------- reaction

a.Endothermic

b.oxidation

c.precipitate

d.None

17. Which option denotes a double displacement reaction?

a. A+ B+C

b. A+B------ C

c. AC+ BD------- AD+BC

AC + B------- AB + C

18. Sublimation of solid ammonium chloride is a

a. chemical change

b. Physical change

c. Both

All of these

19. Mg +2HCl------- MgCl2 + —

a. N2

b. O2

c. Br2

20. Heating sugar is a

a. decomposition reaction

b. Displacement reaction

c. Double displacement reaction

Combination reaction

21. Magnesium ribbon burns with a dazzling white flame and changes into a white powder. What is the

chemical name of this powder and when mix with water, it turns?

(a) MgO, turns blue litmus red.

(b) ) MgO, turns red litmus blue.

(d) Mg2O, turns blue litmus red.

22. When lead nitrate powder heated in a test tube brown fumes emitted which is

(a) O2 (b) N2O

23. The apparatus given in the adjoining figure was set up to demonstrate electrical conductivity.

Which of the following statement(s) is (are) correct?

(i) Bulb will not glow because electrolyte is not acidic.

(ii) Bulb will glow because HCl is a strong acid and furnishes ions for conduction.

(iii) Bulb will not glow because circuit is incomplete.

(iv) Bulb will not glow because it depends upon the type of

Electrolytic solution.

(a) (i) and (iii) (b) (ii) and (iv)

24. Which of the following processes involve in chemical reactions?

(a) Storing of Oxygen gas under pressure in a gas cylinder.

(b) Liquefaction of air.

(d) Heating copper wire in presence of air at high temperature.

25. Which among the following is(are) double displacement reaction(s)?

(a) Pb + CuCl2 PbCl2 + Cu

(b) Na2SO4 + BaCl2 BaSO4 + 2NaCl

(d) CH4 + 2O2 CO2 + 2H2O

26. We store silver chloride in a dark coloured bottle because in sunlight it turns:

(a) White which is Silver Oxide.

(b) Black which is Silver Hydroxide.

27. A shiny brown coloured element ′X′ on heating in air becomes black in colour. Name the

element ′X′ and the black coloured compound formed.

(a) Silver and silver oxide.

(b) Calcium and Calcium oxide.

(d) Aluminium and Aluminium oxide.

28. The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and

taste is called:

(a) anti - oxidation (b) reduction

29. Which type of reaction is this?

C6H12O6 + 6O2 → 6CO2 + 6H2O

(a) Exothermic reaction

(b) Endothermic reaction

(d) Decomposition reaction

30. On immersing an iron nail in CuSO4 solution for few minutes, you will observe

(a) no reaction takes place

(b) the colour of solution fades away

(d) the colour of solution changes to green

31. A student added dilute HCl to a test tube containing zinc granules and made following

observations: -

(a) the zinc surface became dull and black

(b) a gas evolved which burnt with a pop sound

(d)the solution becomes green in colour

32. A substance ‘X’ is used in white-washing by a painter and is obtained by heating limestone in the

absence of air. Identify ‘X’.

(a) CaOCl2 (b) Ca (OH)2 (c) CaO (d) CaCO3

33. Sita buys a silver jewellery and used to wear that. After a long time of use she observed that ,When

silver jewellery is exposed to air it gets a black coating of

(a) AgNO3(b) Ag2S(c) Ag2O(d) Ag2CO3

34. Assertion (A) : In electrolysis of water, the volume of hydrogen liberated is twice the volume of

oxygen formed.

Reason (R) : Water (H20) has hydrogen and oxygen in the ratio of 1:2 by volume.

35. Rahul took a white colour powder in a china dish and put in the sun. After some time he observes

that the powder turns grey. What may be the white colour powder taken?

(a) AgCl (b) Ca (OH)2 (c) CaO (d) CaCO3

36. Ronit found that a green coating created in rainy season around the copper tumbler present in his

house. He asked to his science teacher about the green coating. What may be the green coating?

(a) CuCl2 (b) Ca (OH)2 (c) Cu(OH)2 (d) CuCO3

37. Arushi’s Copper ring fall in fire due to carelessness. She found that her shiny brown Copper ring

turns into black. What may be the black colour coating formed?

(a) CuCl2 (b) CuO (c) Cu(OH)2 (d) CuCO3

38. During burning of magnesium, Teacher asked the students to wear sun glasses to protect their eyes

from white dazzling light as it:-

(a) damage the retina (b) leads to loss of our vision

39. Fermentation of grapes is considered as a chemical reaction. Three students gave their opinion.

Which may be opinion of their teacher:-

(a) chemical change

(b) sugar in grapes converts into alcohol

(d) all the above

40. Raju took two salt solutions and mix together. Which of the following observations is / are not

correct about the given equation:-

Pb(NO3)2 (aq) + 2 KI (aq) → PbI2(s) + 2KNO3 (aq)

(a) PbI2 is yellow precipitate insoluble in water

(b) It is precipitation reaction

(d) It is very slow reaction

41. The following chemical equation does not represent a chemical reaction that can take place.

3Fe (s) + 4H2O---→ Fe3O4(s)

State what needs to be changed in the above equation for it to represent the correct reaction between

Fe and H2O.

42. Tina was comparing combination reactions with decomposition reactions.

Which class of substances may be the product of a decomposition reaction but not a product of a

combination reaction.

43. A strip of copper was placed in a beaker containing zinc sulphate solution.

On observing the strip next day , it was noticed that

a) The copper strip remained as it was

b) The copper strip became thinner

c) The copper strip became thicker

d) The colour of the strip changed

44. Solutions of copper sulphate , iron sulphate and zinc sulphate are prepared and marked I, II and III

respectively.

Few pieces of aluminium are added to each solution. After sometime , a change will be observed in

a)I and II b) II and III

c) III and I d) All the three

45. PbS reacts with ozone and forms PbSO4.

As per the balanced equation , molecules of ozone required for every one molecule of PbS is/ are-

4 b) 3 c) 2 d) 1

46. A piece of Magnesium ribbon is added to flask containing dil. HCl . Hydrogen gas is formed which

is collected is the measuring cylinder. The amount of hydrogen formed with time is plotted in a

graph. The line on the graph indicates the rate of chemical reaction occurring in the flask.

At what time is the reaction rate the fastest in the flask?

a) at 1 minute b) at 3 minutes

b) at 4 minutes d) at 6 minutes

47. Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by the

liberation of heat. This process is called slaking of lime . Calcium hydroxide dissolves in water to

form its solution called lime water. Which among the following is /are true about slaking of lime and

the solution formed?

i)it is an endothermic reaction

ii)it is an exothermic reaction

iii)the pH of the resulting solution will be more than seven

iv)the PH of the resulting solution will be less than seven

a) i and ii b) iii and iv c)i and iv d) ii and iii

48. Identify the chemical reaction that correctly represents production of Magnesium Nitride by burning

Magnesium metal in a pure nitrogen atmosphere from the following –

a) Mg3N2(s) -→Mg (g) + N2(g)

b) Mg + N2--→ Mg3N2

c) 3MgN2(g)---→ Mg3N2(g)

Mg3N2 ---→ 3Mg + N2

49. Mohan took pure water for electrolytic decomposition of water but did not he see any bubbles near

the electrodes . Give reason . Why?

50. Given below is the balanced equation for the thermal decomposition of Lead nitrate .

2Pb(NO3)2 ---

Heat

---→ 2 PbO + 4NO2 + O2

Which of the following information does the cofficients of PbO and NO2 in the equation (2 and 4

respectively ) tell us ?

(a)The ratio of the number of moles produced of the two substances.

(b)The ratio of the number of atoms in the two substances.

(d) The ratio of the densities of the two substances.

51.

VSA 2 MARKS EACH

1. Illustrate an example of oxidation reaction that you observe in everyday life.

2. What is the difference between the following two reactions?

i. Mg + 2HCl → MgCl2 + H2

ii. NaOH + HCl → NaCl + H2O

Suggest a valid reason for each of the reaction.

3. i. Identify the reducing agent in the following reaction.

Fe2O3 + 3CO→ 2Fe + 3CO2

ii. What is Reduction reaction?

4. What happens when iron nails are immersed in copper sulphate solution?

5. Balance the following equations

1.Cl2 + 2KI--2KI---KCL+ I2

2. C2H5OH+ O2 —--- CO2 + H2O+ heat

6. Write the balanced chemical equation a

1. hydrogen + chloride---------- hydrogen chloride

2. Zinc oxide + carbon--------- Zinc + carbon monoxide

7. A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance

is formed. Write the chemical reaction involved and also mention the type of the chemical reaction?

8. Translate the following statement into chemical equation and balance it. Also write the name of

reaction.

Barium Chloride reacts with aluminium sulphate to give Aluminium Chloride and a precipitate of

Barium Sulphate.

9. Why decomposition reactions are called the opposite of combination reactions? Write equations for

these reactions.

10. Aman mixes an aqueous solution of Sodium Sulphate (Na2SO4) and an aqueous solution of Copper

Chloride (CuCl2).

Will this lead to a double displacement reaction? Justify your answer.

11. A student dropped few dropped few pieces of marble in dil .HCl in a test tube . The gas evolved was

passed through lime water. What change would you observe in lime water?

Write chemical reaction for both the changes.

12. Eight identical iron blocks were placed on the ground in two arrangements X and Y as shown below .

The block arrangements were kept moist by sprinkling water every few hours.

Which of these arrangements is likely to gather more rust after ten days ? Justify your answer.

13. Balance the following chemical equations.

a) Fe2O3

+ Al → Fe + Al2O3

b) Pb(NO3)2 → PbO+ NO2 +O2

14. Padmaja conducting the following experiment. She could not understood the following. Let us help

her to understood.

a)Name the brown fume and write its molecular formula.

b)Name the brown residue left in the test tube.

15. While conducting the following experiment:-

a)How will you verify the hydrogen gas?

b) Write the balanced chemical equation for this reaction.

SA 3 MARKS EACH

Carefully observe the reactions taking place in above diagram and answer the following

questions.

a. Write the chemical reaction taking place.

b. Name the type of reaction.

c. 28Write one use of the above reaction.

2. A metal ‘X’ acquires a green colour coating on its surface on exposure to air.

i. Identify the metal ‘X’.

ii. Name the process involved.

iii. Name one method to prevent the process.

3. When potassium iodide solution is added to a solution of lead (II) nitrate in a test-tube, a

precipitate is formed.

i. Name the compound precipitated.

ii. What is the colour of the precipitate?

iii. Write a balanced chemical equation for this reaction.

4. a. Why can't a chemical change be normally reversed?

Why is it always essential to balance a chemical equation?

5. What happens when a piece of

1.aluminium metal is added to dilute hydrochloric acid?

2. Silver metal is added to copper sulphate solution?

6. A metal is treated with dil.H2SO4.The gas evolved is collected by the method . Answer the

following

1.write the method of collection of the gas.

2. Name the gas.

3. Is the gas soluble or insoluble in water?

7. What is redox reaction? Identify the substance oxidised and the substance reduced in the following

reactions.

(i) 2PbO + C 2Pb + CO2

(ii) MnO2 + 4HCl MnCl2 + 2H2O + Cl2

8. Write balanced equations for the following also write the type of reaction involved.

(i) Aluminium + Bromine —–> Aluminium bromide

(ii) Calcium carbonate—–> Calcium oxide + Carbon dioxide

(iii) Silver chloride—–>Silver + Chlorine

9. A student has mixed the solutions of lead(ii) nitrate and potassium iodide.

(i) What was the colour of the precipitation formed? Can you name the Precipitated?

(ii) Write the balanced chemical reaction for this reaction.

(iii) What type of reaction is it?

10. A teacher conducting the electrolysis of water. Find out the solution of the following doubt arise by

the students:-

i)why does the amount of hydrogen is double than the amount of oxygen?

ii)What is the role of dil.sulphuric acid in this experiment?

iii)Name the type of reaction.

11. Find out the type of chemical reactions.

a) CaCO3 (s) Heat CaO(s) + CO2 (g)

b) Zn(s) + CuSO4 (aq)→ ZnSO4 (aq) + Cu(s)

c)Pb(NO3)2(aq) + KI (aq) → PbI2(s) + KNO3 (l)

12. Translate the following statements into chemical equations and then balance them:-

(a)Hydrogen gas combines with nitrogen to form ammonia.

(b)Hydrogen sulphide gas burns in air to give water and sulpur dioxide.

13. Geeta has been collecting silver coins and copper coins. One day she observed a black coating on

silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for

these coatings? Write the chemical names of black and green coatings.

14. Poonam finds a paper with a white substance in the chemistry lab. She keeps the paper near the

window of the lab and comes back to pick it up after 5 hours. She noticed that the white substance

had turned grey.

(a) What should be the substance on the paper?

(b) The substance changed from white to grey. Write the chemical equation for this change.

15. Which of these could increase the rate of reaction ? Circle Yes /No for each row.

Will this increase the rate of reaction? Yes/ No

a) Adding more acid to the flask Yes/ No

b) Heating the contents Yes/ No

c) Adding a catalyst Yes/No

16.

17.

18.

CASE BASED QUESTIONS 4 MARKS

1. 2g of ferrous sulphate is heated in a dry boiling tube.

i. List any two observations.

ii. Name the type of chemical reaction taking place

iii. Write the chemical equation for the following reaction.

2. Classify the following reactions into different types:

i. 2KBr + Cl2 -→ 2KCl + Br2

ii. Ca (OH)2 + H2SO4 --→ CaSO4 + 2H2O

iii. ZnCO3→ZnO + CO2

iv. CH4 + 2O2 ---→ CO2 + 2H2O + Heat

3. 2 g of ferrous sulphate crystals are heated in a boiling tube.

(i) State the colour of ferrous sulphate crystals both before heating and after heating.

(ii) Name the gases produced during heating.

(iii) Write the chemical equation for the reaction.

(iv) Write the name of reaction.

4. Identify the type of reaction from the following equations: (2012)

(i) CH4 + 2O2 → CO2 + 2H2O

(ii) NaBr (aq) + AgNO3 (aq) → AgBr (s) + NaNO3 (aq)

(iii) CaO + H2O → Ca(OH)2

(iv) CuSO4 + Zn → ZnSO4 + Cu

5. Anshuman conducting the following experiment. Find out the following related to this reaction.

a)Write the chemical formula of this two reactants taken in aqueous form?

b)What is the colour change happen after the reaction?

c)Name the type of chemical reaction.

d)Name the precipitate produce in this reaction.

6. Prateek conducting the following experiment. Find out the solution for the following doubt related to

this reaction.

a)Why does the colour change happen to the copper?

b)Name the type of chemical reaction.

c)Write the balanced chemical equation for this.

d)How can prateek get back the shiny brown copper again?

7. On heating blue coloured powder of Copper(III) Nitrate in a boiling tube, Copper Oxide, Oxygen gas

and a brown gas X is formed.

(a)Write a balanced chemical equation of the reaction.

(b)Identify the brown gas X evolved.

(c)Identify the type of reaction.

(d)What could be the pH range of aqueous solution of the gas X?

8. Study the given figure and answer the following questions-

i) Before burning a Magnesium ribbon it is rubbed with sandpaper. Why?

ii) State the type of chemical reaction.

iii) Write the balanced chemical equation for this chemical change.

iv) What will happen if water is added to the product of this reaction?

LA ( 5MARKS)

i. State your observations from the above diagram

ii. What is the black substance and why it is formed?

iii. Write the balanced chemical equation for the above reaction.

iv. What will happen if hydrogen gas is passed over the product formed in the above

reaction?

v. Define Oxidation reaction.

2 On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite

then a white ppt is obtained.

1.write a balanced chemical equation of the reaction involved.

2. On adding dilute HCl to the reaction mixture

White ppt disappears.

3 a) Write one example for each of decomposition reaction carried out with help of

(i) Electricity (ii) Heat (iii) Light

(b) Which of the following statements is correct and why copper can displace silver from silver

nitrate and

Silver can displace copper from copper sulphate solution.

4 Question No. i) to v) consist of two statements – Assertion (A) and Reason (R). Answer these

questions selecting the appropriate option given below:

(a) Both A and R are true and R is the correct explanation of the Assertion.

(b) Both A and R are true but R is not the correct explanation of the Assertion.

(d) A is false but R is true.

(e)Both the statements are wrong.

i)Assertion (A) : When HCl is added to zinc granules, a chemical reaction occurs.

Reason (R) : Evolution of a gas and change in colour indicate that the chemical reaction is taking

place.

ii) Assertion (A) : Calcium carbonate when heated gives calcium oxide and water.

Reason (R) : On heating calcium carbonate, decomposition reaction takes place.

iii) Assertion (A) : Brown fumes are produced when lead nitrate is heated.

Reason (R) : Nitrogen dioxide gas is produced as a by product due to the decomposition of lead

nitrate.

iv) Assertion (A): Pungent smelling gas is produced when sulphur burns in air.

Reason (R) : Sulphur trioxide is formed on reaction of sulphur with oxygen.

v)Assertion (A) : In a reaction of copper with oxygen, copper serves as a reducing agent.

Reason (R) : The substance which gains oxygen in a chemical reaction acts as a reducing agent

5 A student performed the experiment of heating ferrous sulphate crystals in a boiling tube. He smelt

fumes of a pungent gas and saw colour of ferrous sulphate disappears.

(i)Name the gases produced during heating.

(ii)Write the balanced chemical equation.

(iii)State the colour of Ferrous Sulphate crystals both before heating and after heating.

(iv)Why does the colour of crystal disappear?

(v)Identify the nature of this chemical reaction.

ANSWERS FOR MCQs

1. c Magnesium ribbon burns with brilliant white light

2. a. It is a decomposition reaction and endothermic in nature

3. d. Combustion of liquified petroleum gas

b. Pb (NO3)2

5. b. ii and iii

6. c. ii and iv

7. a. Both Assertion and Reasons are true and reason is the correct

explanation of Assertion.

8. c. Assertion is true, but Reason is false

9. c. Assertion is true, but Reason is false

10. a. Both Assertion and Reasons are true and reason is the correct explanation of Assertion

11. c

12. d

13. c

14. b

15. b

16. b

17. d

18. c

19. d

20. a

21. (b) ) MgO, turns red litmus blue

22. (d) NO2

23. (c) (ii) only

24. (d) Heating copper wire in presence of air at high temperature.

25. (ii) Na2SO4 + BaCl2 BaSO4 + 2NaCl

26. (c) Grey which is Silver.

27. (c) Copper and Copper oxide.

28. (c) rancidity

29. (a) Exothermic reaction

30. (d) the colour of solution changes to green

31. (B)a gas evolved which burnt with a pop sound

32. (C) CaO

33. (B) Ag2S

34. (A) Both A and R are true and R is the correct explanation of the Assertion.

35. (A) AgCl

36. (D) CuCO3

37. (B) CuO

38. (C) both (a) & (b)

39. (D) all the above

40. (B) It is precipitation reaction

41. Water should be in the form of steam not liquid.

42. An element.

43. a) The copper strip remained as it was.

44. d) All the three

45. a) 4

46. a) 1 minute

47. d) ii and iii

48. b)Mg + N2--→ Mg3N2

49. Pure water is a bad conductor of electricity as it does not have sufficient amount of ions i.e, charge

carriers.

50. (a)The ratio of the number of moles produced of the two substances.

51.

ANSWERS FOR VSA ( 2 MARKS)

1 Iron particles are shiny when new but get coated with reddish brown powder when left for

some time. This process is known as rusting of iron which is an example of oxidation

reaction.

2 i. Mg is more reactive than H, hence displaces hydrogen. It is a displacement

reaction

ii. Exchange of ions between the reactants occur. It is a double displacement

reaction.

3 i. CO is a reducing agent as it removes oxygen from Fe2O3 and causes its

reduction.

ii. Correct definition of reduction reaction

4 Fe + CuSO4 —------- FeSO4+ Cu

Displacement reaction

5 1. Cl2+ 2KI —------- 2KCL + I2

C2H5OH + 3O2 —-------2CO2+ 3H2O

1. H2+ Cl2-------- 2HCl

ZnO+ C —---- Zn + CO

7 KCl (aq) + AgNO3 (aq) AgCl (s) + KNO3 (aq)

It is a double displacement reaction. It is also a precipitation reaction as AgCl is white precipitate.

8 3BaCl2 (aq) + A12 (SO4)3(aq) 3BaSO4(s) + 2AlCl3 (aq)

Double displacement OR precipitation reaction.

9 In decomposition reaction, a compound is broken down into simpler compounds or elements,

e.g. CuCO3 (s) CuO (s) + CO2 (g)

In Combination reaction is a reaction in which two or more elements or compounds combine to form

a new compound,

e.g. N2 (g) + H2 (g) 2NH3 (g)

Thus, decomposition and combination reactions are opposite to each other.

10 a) Fe2O3 + 2Al → 2 Fe + Al2O3

b) 2Pb (NO3)2 → 2PbO + 4NO2 +O2

11 a)Brown fume is nitrogen dioxide and write its molecular formulais NO2.

b)Lead oxide (PbO)

12 a) The gas will burn itself by making a pop sound.

b) Zn + H2SO4 ZnSO4 + H2

13 No. Because, anyone of the products must be insoluble in water so that a precipitate can be formed.

14 Carbon dioxide gas is evolved.

CaCO3 + 2HCl ---→ CaCl2 + H2O + CO2

15 Y.

Rusting is a surface phenomenon.

ANSWERS FOR SA ( 3 MARKS)

1. sunlight

i. 2AgCl(s)----------→ 2Ag(s) + Cl2(g)

ii. Photolysis or photochemical decomposition reaction

iii. It is used in black and white photography

2. i. The metal ‘X’ is copper (Cu)

ii. The process involved is corrosion

iii. We can prevent the process by painting

3. i. PbI2(lead iodide)

ii. Yellow ppt.

iii. Pb (NO3)2(aq) + 2KI (aq) -→ PbI2 + 2KNO3

4. 1.due to different reactants.

2. Satisfy the law of Conservation of mass.

5. 1. AlCl3 produces with H2 gas.

Silver is less reactive than copper. So not be displaced.

6. 1.downward displacement of water.

2. Hydrogen

3. The gas is insoluble in water. So it can be collected over water.

7. Those reactions in which oxidation and reduction takes place simultaneously are called redox

reactions.

(i) PbO is getting reduced and C is getting oxidised.

(ii) MnO2 is getting reduced and HCl is getting oxidised.

8. (i) 2Al (s) + 3Br2 (g) 2AlBr3 (s) Combination reaction

(ii) CaCO3 (s) CaO + CO2 Decomposition reaction

(iii) 2AgCl (s) 2Ag (s) + Cl2 (g) Decomposition reaction

9. (i) Lead Iodide is the precipitation. It is yellow in color.

(ii) PbNO3+KI→PbI2+KNO3

(iii) Double displacement OR precipitation reaction.

10. i) In water Hydrogen and Oxygen are present in the ratio 2:1 according to their volume. So during

electrolysis of water the amount of hydrogen is produced is double than the amount of oxygen.

ii)Water is poor conductor of electricity. To make it good conductor few drops of dil. Sulphuric acid

is added to it.

iii)It is decomposition reaction.

11. a) It is decomposition reaction.

b) It is displacement reaction.

c) It is double displacement reaction.

12. a)H2 + N2 2NH3

b)2H2S + 3O2 2H2O + 2SO2

c)2K + 2H2O 2KOH + H2

13. Corrosion.

Black coating due to formation of Ag2S.

Green coating is due to formation of CuCO3. Cu(OH)2 .

14. (a) Silver Chloride AgCl

(b) 2AgClsunlight

--→2Ag (s) + Cl2

15. (a) NO (b) Yes (c) Yes

ANSWERS FOR CBQ ( 4 MARKS)

1. i. Green colour of Feso4 disappears and reddish-brown solid is formed, smell of

burning sulphur

ii. Decomposition reaction

heat

iii. 2FeSO4(s)---⟶Fe2O3(s)+SO2(g)+SO3(g)

2. i. Single Displacement

ii. Double displacement

iii. Decomposition

iv. Exothermic

3. (i) The colour of the ferrous sulphate crystals is green before heating and changes to brown after

heating.

The colour of the crystals changes due to the formation of ferric oxide.

(ii) During heating sulphur dioxide (SO2) and sulphur trioxide (SO3) are produced.

(iii)

(iv) Decomposition reaction

4. (i) Redox reaction

(ii) Double displacement reaction

( iii) Combination reaction

(iv) Displacement reaction

5. a)BaCl2 and Na2SO4

b) The solution changes to white colour.

c) ) It is double displacement reaction.

d) The precipitate produce in this reaction is barium sulphate.

6. a)A black colour coating created around the copper.

b) It is redox reaction.

c)2Cu + O2 2CuO

d) Prateek can get back the shiny brown copper again by passing hot hydrogen gas over this black

compound.

7. (a)2Cu(NO3)2 (s) ---heat------→ 2CuO(s) + 4NO2 (g) + O2(g)

(b) X= NO2

(d) 0-7

8. (a) Because, to remove the coating of basic Magnesium oxide .

(b) Combination reaction

(d)Magnesium Hydroxide is formed.

KEY 5 MARKS

1 i. The copper powder is heated in the above reaction forming copper oxide

ii. The black substance is copper (II) oxide. This is because oxygen is added to

copper and copper oxide is formed

heat

iii. 2Cu + O2 --------→ 2CuO

iv. If hydrogen gas is passed over CuO the black coating on the surface turns brown

as the reverse reaction takes place and copper is obtained.

Heat

CuO + H2 -----------→ Cu + H2O

v. The process in which oxygen is added to a substance or hydrogen is removed

from a substance

2 1. BaCl2 + Na2SO3-------- BaSO3 + 2NaCl

BaSO3+ HCl —-------BaCl2+ SO2 +H2O

3 (a) (i) 2H2O 2H2 (g) + O2 (Electricity)

(ii) CaCO3 CaO + CO2 ( Heat)

(iii) 2AgBr 2Ag + Br2 (Sunlight)

(b) Copper can displace silver from silver Bromide because Copper is more reactive than silver

Cu + 2AgNO3(aq) Cu(NO3) (aq) + 2Ag(s)

4 i)(a) Both A and R are true and R is the correct explanation of the Assertion.

ii)(d) A is false but R is true.

iii)a) Both A and R are true and R is the correct explanation of the Assertion.

iv)(c) A is true but R is false.

v) (a) Both A and R are true and R is the correct explanation of the Assertion.

5 (a) SO2 and SO3

(b) 2FeSO4 ---Heat--→ Fe2O3 + SO2 + SO3

(d) On heating water in the crystal evaporates.

(e) Thermal decomposition reaction

KVS ZIET BHUBANESWAR

CBTI X SCIENCE CH 2-ACIDS BASES AND SALTS

Q. NO QUESTION

MCQ s 1 MARK EACH

1. Sodium hydroxide is an ionic compound cannot conduct electricity but when it added to water it

conducts electricity why?

a. ions are in free state in solid

b. ions are free in aqueous solution

c. ionic compound never conducts electricity

d. ionic compound always conducts electricity

When any metal reacts with acid it forms metallic salt and release hydrogen gas. Which of the

following reaction takes place here?

(a) combination reaction

(b) displacement reaction

(d) decomposition reaction

3. Bleaching powder is prepared by mixing two substance X and Y

Which of the following is the correct pair of X and Y

a. X- calcium oxide and Y-chlorine

b. X- calcium hydroxide, Y-Oxygen

c-X -Calcium hydroxide Y- Chlorine

d- X-Calcium oxide Y- Oxygen

4. When soap is added to turmeric the color of turmeric changes to red this indicates that

a. turmeric when added to acid changes to red

b. turmeric when added to base changes to red

c. turmeric reacts with both acids and bases

d. turmeric neither reacts with acid nor with bases

5. A solution of pH 5 is filled in one beaker and another of pH 9 in another beaker. A few drops of

methyl orange added to both how the color changes

a) it will become red in both

b) it will become yellow in both

c) it will become red in beaker 1 and yellow in beaker 2

d) it will become yellow in beaker 1 and red in beaker 2

6. When acid reacts with metal carbonate then a gas is released which makes the lime water milky what

is the gas released

a. Hydrogen

b. oxygen

c. nitrogen

d. Carbon dioxide

7. If we will test the pH of blood then it will come in which of the color ranges of the pH scale

a. Red b. Yellow C. green d.Orange

Which color will indicate a strong acid in the pH paper?

a. Red b. Yellow C. green d. Violet

When dilute hydrochloric acid is added to a solid X, a gas Y is formed along with the formation of

the salt of the solid. What could be X and Y?

a) X: zinc; Y: oxygen

b) X: zinc; Y: hydrogen

c) X: copper; Y: oxygen

d) X: carbon; Y: hydrogen

10.

When hydrochloric acid having pH less than 7 reacts with sodium hydroxide having pH more than 7

then sodium chloride will be formed with the removal of water.

What will be the pH of the salt

a. more than 7 b. less than 7

c. equal to 7 d .can not be determined

11.

Suhana takes three beakers, A, B and C and adds aqueous solutions of glucose, alcohol and dil HCl,

respectively in each beaker, as shown in the setup above. In which beaker the bulb will not glow

a)A and C b)B and C c)A and B d) All the three beakers.

12. Anita put a drop each of dil. Acetic acid and dil. HCl acid on pH paper and compared the colors of

both respectively. The correct Observation of color by Anita will be

a) Light yellow and Red b) Red and Orange

c) pink and orange d) Red and Pink

13. The figure here shows an important process. Which of the

following process does it exhibit?

a) Hydration b) Neutralization

c) Dehydration d) Dilution.

14. Few drops of NH4Cl Sol. Was put on Universal indicator paper and it’s color changed to pink. Study

the following table and choose the correct option.

NH4Cl is a Salt of:

options Nature Acid and Base Strength pH range

a) Acidic Weak acid and Strong

base

< 7

b) Basic Weak acid strong base >7

c) Acidic Strong acid and weak

base

< 7

d) Basic Strong acid and strong

base

15. Which of the following are present in a dilute aqueous solution of hydrochloric acid?

a) H3O

+ + Cl-

b) H3O

+ + OH-

c) HCl + OH-

d) Cl-

+ OH-

16. Study the figure given alongside and choose the correct statement from the following.

a) Cu is more reactive than Mg and Zn

b) Zn is more reactive than Cu and Mg

c) Mg is more reactive than Zn and Cu

d) All the three metals have the same reactivity.

17. During electrolysis of brine, a gas ‘P’ is liberated at anode and another gas ‘Q’ is liberated at

cathode. ‘P’ is used for disinfecting water while ‘Q’

is used in aviation fuels. The correct identification of ‘P’ and ‘Q’ irrespectively is:

a) Cl2 and H2 b) H2 and O2

c) H2 and Cl2 d) O2 and H2

18. A compound X of sodium is used in Soda acid fire extinguisher. This compound can also be used,

a) in removing permanent hardness of water.

b) as an antacid

c) as a cleaning agent

d) In the manufacturing of soap.

19. Assertion: Ammonium Hydroxide is a weak base.

Reason: Phenolphthalein becomes pink when added to ammonium hydroxide.

20. Assertion: All metal carbonates react with acids to give salt, water and carbon dioxide.

Reason: All metal oxides react with water to give salt and acid.

21. Equal volumes of hydrochloric acid and sodium hydroxide solutions of same concentration are

mixed and the pH of the resulting solution be checked with a pH paper. What would be the colour

obtained?

a. Red. b. Yellow

c. Yellowish green. d. Blue

22. Assertion: Ammonium hydroxide is weak base.

Reason: Phenolphthalein becomes pink in NH4OH

(a) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the

Assertion.

(b) Both the Assertion and the Reason are correct but the Reason is not the correct explanation of the

Assertion.

(d) Assertion is false but the reason is true

23.

Which of the following statements can be concluded from this picture.

(I) Acid, Base and Salt are ionic compounds

(ii) Due to this they can conduct electricity.

(iii) Acid and Base Reacts to form salt.

(a) Only (i) and (ii)

(b) Only (i)

(d) All (i), (ii) and (iii)

24.

Identify the type of reaction occurs here

(i) Neutralization reaction

(ii) Exothermic reaction

(iii) Redox reaction

(iv) Double displacement reaction

(a) Only (i), (ii) and (iii)

(b) Only (i) and (iv)

(d) Only (i)

25.

To identify the evolved gas Anil brought one burning match stick near the face of test tube. What he

might have observed and concluded.

(a) Matchstick extinguished due to formation of carbon dioxide.

(b) Matchstick burnt with pop sound due to production of hydrogen gas.

(d) Matchstick burnt with pop sound due to the formation of carbon dioxide.

26. What is the pH value of a salt formed by a weak acid and a strong base?

(a) Greater than 7. (b) equal to 7

27. A solution has pH 4. It is diluted by adding it with water. How will it affect the pH of the solution?

(a) The pH will increase

(b) The pH will decrease

(d) It can't be said

28. A few drops of phenolphthalein indicator were added to an unknown solution A. It Acquired pink

colour. Now another unknown solution B was added to it drop by Drop and the solution becomes

colorless. Predict the nature of A & B.

(a) A- Acid, B- base

(b) A- Base, B- acid

(d) A- Base, B- Salt

29. Plaster of Paris is stored in a moisture proof container because:

(a) It absorbs moisture from the atmosphere and becomes hard.

(b) It changes its colour.

(d) It produce foul smell.

30. What is the number of water molecules present in copper sulphate pentahydrate?

i. 5. ii. 7. iii. 10. iv. 2

31. The pH of the gastric juices released during digestion is

a) less than 7 b) more than 7

c) equal to 7 d) equal to 0

32. Which of the following is/are natural indicators?

a) Hydrangea b) Petunia

c) Geranium d) All of the above

33. If a person is suffering from acidity after overeating,you should suggest him to take

a) lemon juice b) vinegar

c) baking soda solution d) all of these

34. Observe the graph drawn between concentration of H3O+ Vs pH.Observe the graph carefully and

answer the questions that follow:

This graph shows

a) Concentration of H3O+ increases,pH of solution decreases

b) Concentration of H3O+ decreases,pHof solution increases

c) Concentration of H3O+ and pH both decreases

d) Concentration of H3O+ and pH both increases

35. Brine is an

a) aqueous solution of sodium hydroxide

b) aqueous solution of sodium carbonate

c) aqueous solution of sodium chloride

d)aqueous solution of sodium bicarbonate

36. Which of the following salts does not contain water of crystallization?

a) Blue vitrol b) Baking soda

c) Washing soda d) Gypsum

37. Acid present in tomato is

a) Methanoic acid b) Acetic acid

c) Lactic acid d) Oxalic acid

38. Which of the following solution will turn phenolphthalein pink?

a) HCl b) CO2

c) KOH d) H2SO4

39. On adding dilute HCl to copper oxide in a beaker the solution turns blue green due to formation of

a) Copper(II) hydroxide b) Copper nitrate

c) Copper(II) chloride d) Copper sulphate

40. Calcium carbonate is the chemical formula of

a) limestone b) chalk c) marble d) all of the above

41. 1. An aqueous solution turns the red litmus solution blue. Excess addition of which of the following

solutions would reverse the change.

(a) Baking Powder

(b) Lime

(d) Hydrochloric Acid

42. The water of crystallization of washing soda is

(a) 10

(b) 9

(d) 1

43. Salt ‘A ‘ commonly used in food products is reactant to produce salt ‘ B’, used in the kitchen for

making pakoras. Salt ‘B’ on heating converts into another salt ‘C’ which is used in manufacturing in

the glass industry. Salt ‘A’, ‘B’ and ‘C’ respectively are

(a) NaHCO3, NaCl, Na2CO3

(b) Na2Co3,NaHCO3,NaCl

(d) NaCl, NaHCO3, Na2CO3

44. Which of the following is treated with chlorine to obtain bleaching powder.

(a) CaSO4

(b)Ca(OH)2

(d) KOH

45. A solution reacts with crushed eggshells to give a gas that turns lime water milky. The solution

contains

(a) NaCL

(b) HCl

(d) LiCl

46. A solution turns red litmus blue, its pH is likely to be

(a) 2

(b) 4

(d) 10

47. Which of the following salt does not contain water of crystallization?

(a) Blue vitriol

(b) Baking soda

(d) Gypsum

48. A student added a metal powder to dilute HCl dilute NaOH solution in two separate test tubes. He

noticed gas bubbles in both the test tubes. When he brought a burning candle near the mouth of

both the test tubes, the gas burns with pop sound. The metal powder used may be

(a) Cu

(b) Zn

(d) Ca

49. A student dipped a blue litmus paper first in dil. HCl and then in dil. NaOH solution. He observed

that the color of litmus paper

(a) Remained blue in both the solution

(b) change blue to colorless

(d) Change to red.

50. At what temperature is gypsum heated to form Plaster of Paris?

(a) 90°C

(b) 100°C

(d) 120°C

51. Fresh milk has a PH of 6.When it changes into curd ,its pH value

a.increase

b. Decrease

c.no change

d. None

52. Write Some characteristics of chemical reaction

a. Change in colour

b. Change in temperature

c. Evolution of gas & formation of ppt

d. All of these

53. C6H12O6 + 6O2—-------------------------6CO2 + 6 H2O

The above reaction is a /an

a. Displacement reaction b . Endothermic reaction

b. C. Exothermic reaction d. Neutralization reac6

54. Which of the following is strong acid?

a. HNO3

b. NaOH

c. KOH

d. NH4OH

55. The Formula of washing soda is

a. FeSO4. 7H2O

b. ZnSO4. 5 H2O

c. Na2CO3. 10 H2O

d. All of these

56. Brine is an aqueous solution of

a. NaCl

b. HCl

c. H2SO4

d. KCl

57. Slaked lime is a

a.CaO

b. Ca(OH)2

c.KOH

d.None

58. Stinging hair of nettle leaves inject a chemical which causes burning pain. This chemical is

a. Ethanoic acid

b. Methanoic acid

c. Oxalic acid

d. Tartaric acid

59. Name the substance used for disinfecting drinking water supply.

a. Baking soda

b. Washing soda

c. Bleaching powder

d. None of these

60. Bases taste

a.Bitter

b.Sour

c.Salty

d.no taste

61. What happens when a solution of an acid is mixed with a solution of a base in a test tube?

(i) Temperature of the solution decreases

(ii) Temperature of the solution increases

(in) Temperature of the solution remains the same

(iv) Salt formation takes place

(a) (i) and (iv)

(b) (i) and (iii)

(d) (ii) and (iv)

62. What is formed when zinc reacts with sodium hydroxide?

(a) Zinc hydroxide and sodium

(b) Sodium zincate and hydrogen gas

(d) Sodium zincate and water

63. An aqueous solution turns red litmus solution blue. Excess addition of which of the following

solution would reverse the change?

(a) Baking powder

(b) Lime

(d) Hydrochloric acid

64. When copper oxide and dilute hydrochloric acid react, colour changes to

(a) white

(b) bluish-green

(d) black

65. Sodium hydroxide turns phenolphthalein solution

(a) pink

(b) yellow

(d) orange

66. Farmers neutralise the effect of Acidity on the soil by adding –

(a) Slaked lime

(b) Gypsum

(d) Baking soda

67. Tomato is a natural source of which acid?

(a) Acetic acid

(b) Citric acid

(d) Oxalic acid

68. At what temperature is gypsum heated to form Plaster of Paris?

(a) 90°C

(b) 100°C

(d) 120°C

69. Lime water reacts with chlorine to give

(a) bleaching powder

(b) baking powder

(d) washing soda

70. Tooth enamel is made up of

(a) calcium phosphate

(b) calcium carbonate

(d) potassium

71.

72.

VSA 2 MARKS EACH

1. When gypsum will be heated a white product will be formed which is used for toy making

,painting etc.

i) What is the formula of plaster of Paris?

ii) What is the number of crystallization present in plaster of Paris.

a. 1/2 b. 2/3 c. 1/4 d.2/5

2. The equation shows the reaction of metal carbonate with acid.

i) HCl + CaCO3 →X +H2O+CO2

What is X

a. CaO b. CaCO3 c.CaCl2 d.Ca(OH)2

ii) When a base reacts with metal carbonate what will be the product formed?

a. salt b. salt and water

c. salt+ water+ CO2 d. No reaction

1.From the taste of different food items foods can be classified as acid and base . students are asked to

prepare a list of acidic food item . a student prepared the following list . which of the following is not

correct for acidic food item list

A. Amla b. orange c. apple d. banana

2. Tomato contains which of the following acids?

a. citric acid b. Lactic acid c. Oxalic acid d. acetic acid

4. Distinguish between baking soda and Washing soda when both are heated.

Write chemical equations for both.

5. Explain with respect to pH change for the following

a) formation of acid rain

b) cause of tooth decay.

6. (i)Observe the caution mark shown in the container and account for the

significance of it.

(ii)Why can acids be not stored in metal containers?

(i) Which of the following liquid may the beaker contain?

a. Vinegar. b. Soft drink

c. Salt water. d. Baking soda solution

(ii) What can be the pH range of the solution?

a. 0 to 7. b. 7.

c. 7 to 14. d. Can't be said

8. Anjali performed the following experiment.

(a) Which process is Anjali wanted to verify through this experiment

(b) List any two more observations did Anjali notice during the experiment along with water droplets.

9. A first aid manual suggests that vinegar should be used to treat wasp sting and baking soda for bee

stings.

(i) What does this information tell you about the chemical nature of the wasp stings

(ii) If there were no baking soda in the house, what other household substance could you use to treat

bee stings?

10. What happens when nitric acid is added with an egg-shell?

11. How will you test for the gas which is liberated when hydrochloric acid reacts with an active metal?

12. 15 ml of water and 10ml of sulphuric acid are to be mixed in a beaker

i) State the method that should be followed with reason.

ii) What is the process called.

13. Salt ‘A’ commonly used in bakery products on heating gets converted into another salt ‘B’ which

itself is used for removal of hardness of water a gas ‘C’ is evolved. The gas ‘C’ when passed through

lime water, it turns milky. Identify ‘A’, ‘B’ and ‘C’.

14. Why does a milkman add small amount of baking soda in the fresh milk before distribution in the

houses ?

15. A housewife found that the cake prepared by her is hard and small. Which ingredient has she

forgotten to add that would have made the cake fluffy ? Give reasons

16. a. What is the PH of blood and pure water?

b. Two solutions have PH values of 2 and 6 respectively, which is stronger?

17. Write Some strong acids. (Any four)

18. What happens when nitric acid is added to an egg-shell?Justify your answer.

19. What happens when nitric acid is added to the eggshells?

20. A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She

forgot to label the solutions, and litmus paper was not available in the laboratory. Since both

the solutions are colourless, how will she distinguish between the two?

21. When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is

utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the

reaction involved

SA 3 MARKS EACH

Baking soda is used for cooking . it is used to make the cake spongy .and it is used to prepare baking

powder

1. What is the chemical formula of baking soda?

a. NaCl b. Na2CO3 c. NaHCO3 d.NH4Cl

2.Which gas makes the cake to swell and makes it spongy

a.H2 b. CO2 c.O2 d. N2

3.How baking powder is prepared? by mixing baking soda with.......

a. citric acid c. lactic acid

c. oxalic acid b. Tartaric acid

When ant bites anyone any base applied to it gives relief from ant bite.

i) what is the acid present in ant bite?

a. formic acid b) lactic acid c) citric acid d) Hydrochloric acid

ii) Which reaction takes place when base is added to ant bite

(a) combination reaction

(b) displacement reaction

(d) decomposition reaction

iii) In our stomach which acid is secreted?

a. formic acid b) lactic acid c) citric acid d) Hydrochloric acid

I)From the above pH scale which are the bases

a. B and C b. A and B c. D and C d. A and D

ii) if a person suffers from acidity he should avoid taking

a. A b. B c. C d. D

iii. Between c and A which is more basic?

4. 1 g of solid sodium chloride is taken in a clean, dry test tube and 2mL of conc. Sulphuric acid is

added is added to it. If the gas evolved is first tested with dry litmus paper and then with wet litmus

paper

a) In which case will the litmus paper change its colour?

b) Give reason for your answer above?

c) What conclusion can be drawn about the nature of the gas evolved?

5. What pH do you expect for the following salt solutions and why?

KCl, CuSO4, Na2CO3.

6. A student placed 10 mL each of HCl and NaOH in two separate

beakers as shown. In beaker 1, 4 mL of NaOH is added whereas in

beaker 2, 4 mL of HCl is added.

a) Explain giving reason, how will the pH in both the beaker,

change?

b) Write the chemical equation of the reaction between the two

compounds.

7. Observe the graph drawn between concentration of H3O

vs pH. Observe the graph carefully and

answer the questions that follow:

(a) The graph shows

(i) Concentration of H3O

increases, pH

of solution decreases.

(ii) Concentration of H3O

decreases, pH

of solution increases.

(iii) Concentration of H3O

and pH both

decreases.

(iv) Concentration of H3O

and pH both

increases.

(b) 'A' is

(i) Strongly acidic. (ii) Strongly basic

(iii) Weakly acidic. (iv) Weakly basic

(i) Strongly acidic. (ii) Strongly basic

(iii) Weakly acidic. (iv) Weakly basic

8. Anjali was feeling burning sensation in her hand due to ant bite. Her brother suggested her to rub the

baking soda at that place. And Anjali did the same and got relief from the ant bite.

(a) Why the ant bite gives the burning sensation ?

(b) How rubbing of baking soda helped her to reduce the pain?

i. NaCO3. ii. Na2CO3

iii. NaHCO3. Iv. CaCO3

9. Observe the following picture and answer the following questions

(a) How will you test for the evolution of hydrogen gas?

(b) Write the name and formula of the other product of this reaction along with hydrogen gas?

i. Combination reaction

ii. Displacement reaction

iii. Double displacement reaction

iv. None of these

10. a) Explain why an aqueous solution of sodium sulphate is neutral

while an aqueous solution of sodium carbonate is basic in

nature.

b) Consider the following salts: Na2CO3.NaCl, NH4Cl,

CH3COONa. Which of these salts will give:

i)acidic solution

ii) neutral solution

iii) basic solution

11. List the important products of the Chlor- alkali process. Write one important use of each.

12. With the help of labelled diagram,show an experimental setup for the reaction of Magnesium with

dilute sulphuric acid.

Give equation of the reaction involved.

13.

14.

15.

16.

17.

18.

CASE BASED QUESTIONS 4 MARKS

1.The aqueous solution of base is called .........

2. when metallic oxide and nonmetallic oxide react with each other what will be the product formed?

3. What will be the pH of nonmetallic oxide?

a. 7 b. more than 7 c. less than 7 d. cannot be determined

4. When a strong acid reacts with weak base which type of product will be formed

a. Acidic salt b. Basic salt

c. CO2 d. none of the above

We have often used washing soda as detergents in our daily life .

a. What is the chemical name of washing soda?

b. Write the equation for preparation of washing soda ?

c. How many water of crystallization is present in washing soda?

i. 5 ii.4 iii .10 iv .1/2

d. What is the use of washing soda?

(a) to make the water alkaline

(b) to change the state of water

(d) to remove the permanent hardness of water

3. The pH values of everyday chemicals typically range from pH 0 to pH 14. Values between 0 and 7

indicate an acidic solution. Values between 7 and 14 indicate a basic solution. A pH of exactly 7

indicates that a solution is neutral, neither acidic or basic. Pure water is usually pH 7.

Turmeric is another natural indicator of pH.

[i] What happens to turmeric stains on clothes when

washed with soap? Why? (1)

[ii]Milk of Magnesia which is used to treat acidity is

basic in nature and hence is able to neutralise the

excessive acid in the stomach. Which appropriate pH

value will it show?

a) 2 b) 6 c) 14 d) 10

[iii] Does a solution with pH 10 have equal, less or more H

ions than of a solution with a pH 6?

(1)

[iv]What will be the [H

] for both solutions, include units in your answer:

• For pH 10, [H+] = _________________

For pH 6, [H+] = _________________ (1)

4. On heating gypsum at 373 K, it loses water molecules and becomes calcium sulphate hemihydrate

(CaSO4 .1⁄2 H2O). This is called Plaster of Paris. Plaster of Paris is a white powder and on mixing

with water, it changes to gypsum once again giving a hard solid mass.

Water of crystallization is the fixed number of water molecules present in one formula unit of a salt.

[i] Half molecule of water is associated with one formula unit of CaSO4. What does this mean?

(1)

[ii]What will happen if Gypsum is heated beyond 373K? Write the equation.

(2)

[iii] Define water of crystallization? (1)

5. Radhika wanted to bake a cake for her mother's birthday. She added baking soda in the batter. But

when she tasted the cake after the baking it tasted bitter.

(a) Explain why the cake tasted bitter with the reaction.

(b) Write one step by which Radhika could have made her cake better.

the taste of the cake bitter.

(d) Baking soda is a/an

i. acid. ii. Base. iii. Acidic salt. iv. Basic salt

6. One of the product of electrolysis of brine is X along with the caustic soda. X is used in the

manufacture of bleaching powder.

(a) Identify X and its state?

(b) Write the chemical equation for preparation of bleaching powder by reacting with X.

household use of bleaching powder.

7. The following questions consist of two statements – Assertion [A] and REASON R]. Answer these

questions selecting the appropriate option given below.

a) Both A and R are true and R is the correct explanation of the

b) Both A and R are true but R is not the correct explanation of

c) A is true but R is false.

d) A is false but R is true.

1. ASSERTION [A] – The acid must always be added to water

with constant stirring.

REASON [R] – Mixing of an acid with water decreases the

concentration of H+

ions per unit volume.

2. ASSERTION [A] – Copper sulphate crystals are wet because

it contains water of crystallisation.

REASON [R] – Water of crystallisationis the fixed number of

molecules of water present in one formula unit of salt.

3. ASSERTION [A] – The aqueous solutions of glucose alcohol

do not show acidic character.

REASON [R] – Aqueous solutions of glucose and alcohol do

not show H+

ions.

4. ASSERTION [A] – HCl gas does on change the colour of dry

blue litmus paper.

REASON [R] – HCl gas dissolves in the water present in wet

litmus paper to form H+

ions.

8. The primary reason behind the formation of the toxic foam is high phosphate content in the waste

water because of detergents used in dyeing industries , dhobi ghat and households. Yamunas

pollution level is so bad that parts of it have been labelled dead as there is no oxygen in it for aquatic

life to servive.

(i) Predict the pH value of the water of river Yamuna if the

reason for froth is high content of detergents dissolved in it.

(a) 10-11 (b) 5-7 (c) 2-5 (d) 7

(ii) Which of the following statements is correct for the water

which detergents dissolved in it.

(a) low concentration of (OH)-

and high concentration of ion

(H3O

)

(b) high concentration (OH)-

and low concentration of ion

(H3O

)

+ ) ion

(d) equal concentration of both (OH-

) and (H3O

+ ) ion

(iii) The table provides pH value of four solution P,Q,R and S

Solution pH value

P 2

Q 9

R 5

S 11

Which of the following correctly represents the solutions in increasing order of their hydronium ion

concentration ?

(a) P > Q > R > S (b) P > S > Q > R

(iv) high content of phosphate ion in river Yamuna may lead to:

(a) decreased level of dissolved oxygen and increased growth of

algae

(b) decreased level of dissolved oxygen and no effect on growth

of algae

algae

(d) decreased level of dissolved oxygen and decreased growth

of algae

10.

11.

12.

LA ( 5MARKS)

1) The image shows the pH values of 5 solutions on a pH scale.

i. Arrange them in decreasing order of acidity.

ii. which of the above will release more hydrogen ion in aqueous solution?

iii. which of the following can be kept in place of solution A

a. NaOH b. CaO c. HCl d. NaCl

iv. Which of the above solution will change a red litmus to blue

a. A b. B c. C d. Both A and B

v. Which of the above solution is the strongest base

a. B b. C c. D d. E

2 (a) What are the substances that are formed at anode and cathode in chlor- alkali process?

(b) Write the balanced chemical equation involved in this process?

(d) State at least one use of the product formed at anode.

(a) Identify the compounds X and Y ?

(b) Write the reaction for X breaking into Y and P.

(d) Write reaction of lime water with P and identify the type of reaction.

4 A) A cloth stripe dipped in onion juice is used for testing a liquid ‘X

’

. the liquid ‘X

’

changes its

odour. Which type of an indicator is onion juice? The liquid ‘X

’

turns blue litmus red. List the

observations the liquid ‘X

’ will show on reacting with the following.

(a) Zinc granules

(b) Solid sodium carbonate

Write the chemical equations for the reactions involved.

(B) Name two chemical indicators.

ANSWERS FOR MCQs

1. B

2. B

3. C

4. B

5. C

6. D

7. C

8. A

9. B

10. C

11. C)

12. A)

13. D)

14. C)

15. A)

16. C)

17. A)

18. B)

19. B)

20. C)

21. c. Yellowish green (NaCl is a neutral salt)

22. Option B (Both the Assertion and the Reason are correct but the Reason is not the correct explanation

of the Assertion.)

23. (a) Only (i) and (ii)

24. (c) Only (i), (ii) and (iv)

25. (b) Matchstick burnt with pop sound due to production of hydrogen gas.

26. (a) Greater than 7

27. (a) The pH will increase

28. (b) A- Base, B- acid

29. (a) It absorbs moisture from the atmosphere and becomes hard.

30. (b) 5

31. a) less than 7

32. d) All of the above

33. c) baking soda solution

34. b)Concentration of H3O+ decreases ,pH of solution increases

35. c) aqueous solution of sodium chloride

36. b) Baking soda

37. d) Oxalic acid

38. c) KOH

39. c) Copper (II) chloride

40. d) all of the above

41. (d) Hydrochloric Acid

42. (a) 10

43. (d) NaCl, NaHCO3, Na2CO3

44. (b)Ca(OH)2

45. (b) HCl

46. (d) 10

47. (b) Baking soda

48. (b) Zn

49. (c) Change first to red and then again to blue

50. (d) 120°C

51. b

52. d

53. c

54. a

55. c

56. a

57. b

58. b

59. C

60. a

61. (d) (ii) and (iv)

62. (b) Sodium zincate and hydrogen gas

63. (d) Hydrochloric acid

64. (b) bluish-green

65. (a) pink

66. (a) Slaked lime

67. (d) Oxalic acid

68. (b) 100°C

69. (c) baking soda

70. (a) calcium phosphate

71.

ANSWERS FOR VSA ( 2 MARKS)

1 I.CaSO4 1⁄2 H2O

ii.1/2

2 i. C ii. D

3 i. D ii. C

4 Baking soda decomposes and releases CO2 forming Sod. Carbonate and water, whereas Washing

soda loses all it’s water of crystallization and become anhydrous. Eqtn

as per Textbook.

5 a) Acid rain occurs when the pH of rain water falls below 5.6

b) Tooth decay begins when the pH in the mouth falls below 5.5

6 i)As acids are corrosive, the label cautions to use the acids carefully or else it might be dangerous.

ii) Because Acids react with metals, and so the metal container will not be able to hold it.

7 (i) d. Baking soda solution, (ii) c. 7 to 14.

8 (a) water of crystallization

(b) 1. Blue colour disappears. 2. crystals become powder like.

9 (a) Basic because vinegar(acid) is being used to neutralise it

(b) Ammonium hydroxide (NH4OH) can be used.

10 Egg –shell contain calcium carbonate. When nitric acid is added to it, carbon dioxide gas is

evolved.The reaction can be given as

CaCO3+ 2HNO3---→Ca(NO3)2+ H2O + CO2

11 Bring a burning matchstick near the gas. It burns with pop sound showing that it is hydrogen.

12 i) The acid is to be added slowly in water to prevent the mixter to be splashed. The reaction is highly

exothermic,therefore constant cooling should be done.

ii) The process is called dilution.

13 The salt A is sodium hydrogen carbonate (baking soda) and is commonly used in bakeries as a

constituent of baking powder. Upon heating, it changes to sodium carbonate B and evolves carbon

dioxide gas C. Sodium carbonate removes hardness from water, while CO2 gas turns lime water

milky.

14 To prevent the spoilage of milk, the milkman adds a very small amount of baking soda to fresh milk.

Baking soda is sodium bicarbonate. It is basic in nature. Addition of baking soda increases the pH of

milk from 6.

15 The most important ingredient must be added while making cake is baking soda,It helps to make the

cake fluffy by producing carbon dioxide in the cake when it is heated and leaves small holes

(bubbles) in it. Hence, the ingredient that she has forgotten to add that makes the cake fluffy is

baking soda.

16 a. The PH of blood varies from 7.36 to 7.42.least basic .

PH of pure water is 7 & its neutral.

b. Solution of PH value 2 strong acid is lesser than the PH value, greater is the hydrogen ion

concentration & stronger is the acid.

17 1.HCL

2.HNO3

3.H2SO4

4.HI

18 CO2 gas is evolved.

Egg shell contains CaCO3 which on reactions with HNO3 release CO2.

19 Eggshells contain calcium carbonate. Calcium carbonate reacts with nitric acid to form

calcium nitrate and carbon dioxide gas.

CaCO3 (s) + HNO3 (aq) → CaNO3 (aq) + CO2 (g) + H2O (l)

20 • We can use phenolphthalein to check which beakers contain acid and which one

contains a base. Phenolphthalein turns colourless in acidic solutions and pink in

basic solutions.

• Apart from that, we can also use other natural indicators, like China rose or turmeric.

• Turmeric is a natural indicator. It is yellow coloured. Turmeric paper turns red when it

is dipped into a basic solution while it does not change its colour with acid.

• China rose is another natural indicator. China rose solution gives dark pink (magenta)

colour with acid and green with base.

21 Zinc metal gives hydrogen gas when treated with dilute sulphuric acid. Hydrogen gas is

utilised in the hydrogenation of oil.

Zn + 2 HCl → ZnCl2 + H2.

Therefore, the gas that evolved is hydrogen.

ANSWERS FOR SA ( 3 MARKS)

1. i. C ii. B iii. C

2. i. A ii. C iii. D

3. i. C ii. A iii. C

4. a) With wet litmus paper

b) When the Dry HCl gas dissolves in the moist litmus paper, it will ionize to form H+

ions.

c) It is acidic in nature.

5. KCl—pH is 7, Neutral salt. CuSO4 --- pH less than 7, Acidic salt. Na2CO3 – pH more than 7,Basic

salt

6. a) Beaker 1- pH will increase, due to decrease of H+

ion conc. per unit volume.

b) Beaker 2- pH will decrease, due to increase in H+

ion conc. per unit volume.

HCl + NaOH --------→ NaCl + H2O

7. (a) (ii) Concentration of H3O+ decreases, pH

of solution increases.

(b) (i) Strongly acidic.

8. (a) Ant bite releases an acid called formic acid which causes burning sensation

(b) Baking soda is basic in nature hence it neutralises the acid produced by ant's sting and reduces the

pain.

9. (a) Will take the burning matchstick near the cork and if it burns with a pop sound that represents the

production of hydrogen gas.

(b) Zinc Sulphate(ZnSO4)

10. a) An aqueous solution of sodium sulphate is neutral because it is formed by the reaction of a strong

acid sulphuric acid and a strong base sodium hydroxide. But aqueous solution of sodium carbonate is

basic in nature because it is formed from a strong base sodium hydroxide and a weak acid carbonic

acid.

b) i) Acidic solution – NH4Cl

ii) Neutral solution- NaCl

iii) Basic solution- Na2CO3,CH3COONa.

11. Products: Hydrogen. Chlorine, Sodium hydroxide

Uses :

Hydrogen: In the production of margarine/ammonia/as a fuel

Chlorine : Water treatment/swimming pools/production of PVC/Pecticide

Sodium hydroxide ; for degreasing metal surfaces/in making soaps and detergents/paper making.

12.

Mg + H2SO4--→ MgSO4 + H2

13.

14.

15.

ANSWERS FOR CBQ ( 4 MARKS)

1. i. alkali ii. Salt + water iii. C iv. A

2. i.. sodium carbonate decahydrate

ii. Na 2 CO 3 ( s ) + 10 H 2 O ( g )--→Na 2 CO 3 . 10 H 2 O ( s )

iii. C iv. d

3. i] Turmeric Stains turn red. Soap contains base, and bases change the color of turmeric to red.

ii] option d) 10

iii] H+ ions will be less,

iv] For pH 10 ,[ H+

]=10-10mol/L , For pH 6, [ H+

]=10-6mol/L

4. i)It means One molecule of water is shared by two formula units of CaSO4

ii) It will become anhydrous CaSO4, which is called ‘dead burnt plaster’.

CaSO4.2H2O------above 373 k----→ CaSO4 + 2H2O.

iii) Water of crystallization is the fixed number of water molecules present in one formula unit of a

salt.

5. (a) 2 NaHCO3 ---------> Na2CO3 + H2O + CO2

Formation of sodium carbonate makes the taste bitter.

(b) By adding some acid like cream tartar or vinegar into it as it will neutralise the basisity of baking

soda.

(d) iv. Basic salt

6. (a) X is Chlorine it is a gas.

(b) Ca(OH)2 + Cl2 → CaOCl2 +H2O.

Household use- Used to disinfect water/Helps to remove moss

7. 1) (b)

2) (d)

3) (a)

4) (a)

8. (i) (a); Detergents being basic increase the pH of water above 7.

(ii) (b); Detergents are basic in nature. So, it has high concentration of hydroxide ion (OH) and low

concentration of hydronium ion (H,O*)

(i) (c); Higher the pH, lower is the hydronium ion concentration.

(iv) (a); Phosphate ion increases the growth of algae which ultimately decrease the level of dissolved

oxygen.

10.

11.

12.

KEY 5 MARKS

1 i. A> B>C > D> E

ii. A

iii. C

iv. C

v. D

2 a) The products are Cl2, H2 and NaOH.

b) 2 NaCl + 2H2O -----

ELECTRIC CURRENT

--→ 2 NaOH + Cl2 + H2

c) This method is called Chlor-alkali Process because the products are chlorine ( chlor) and Sodium

hydroxide

(alkali)

Any one correct use.

3 (a) X- Calcium carbonate (CaCO3). Y- Calcium oxide (CaO)

(b) CaCO3. ----------->CaO + CO2

(d)Ca(OH)2 + CO2 -------------> CaCO3 + H2O, Redox/Exothermic/Neutralization/precipitation

reaction

4 A) Onion juice is an olfactory indicator. Olfactory indicators give one type of odour in acidic

medium and a different medium and a different odour in basic medium. As the liquid X turns blue

litmus red, hence it is an acidic solution.

(a) Acids reacts with active metals such as zinc, magnesium, etc. and evolve hydrogen gas, for

example,

Zn(s) + dil. H2SO4(aq) ------ ZnSO4 + H2(gas)

(b) Acids react with metal carbonates to give carbon dioxides with brisk effervescence.

(B) Phenolphthalein, Methyl orange

KVS ZIET BHUBANESWAR

CBTI X SCIENCE CH_3_Metals and Non-metals

Q. NO QUESTION

MCQ s 1 MARK EACH

1. An element react with oxygen to give a compound with a high melting point.This

compound is also soluble in water. Name this element

(a) Calcium (b) Carbon (c) Silicon (d) Iron

2. Assertion:- Aluminium oxide is an amphoteric oxide.

Reason:- Amphoteric oxides are those which reacts both acid as well as base.

(a) Both A and R are true and R is the correct explanation of A.

(b) Both A and R are true but R is not the correct explanation of A.

(d) A is false , R is true.

3. A:- Chromium oxide is generally reduced to chromium by heating with aluminium

powder.

R- The reduction of chromium oxide by aluminium is highly exothermic.

a) Both A and R are true and R is the correct explanation of A.

(b) Both A and R are true but R is not the correct explanation of A.

(d) A is false , R is true

4. Rakesh immersed a zinc plate in aquous solution of copper sulphate.She noticed a

thick layer of copper on the surface of the zinc plate after an hour. What is the

formula of the colourless solution after the reaction?

(a) Zn

(b) Cu

(d) CuSO4

5. What should Rakesh have done to make reaction faster:-

(a) Use Zn plate

(b)Use piece of Zn flakes

(d)Use CuSO4 solution in higher concentration.

6. A metal X doesn’t liberate Hydrogen from acid but react with oxygen to give black

coloured product. Identify X.

(a) Na

(b) Cu

(d) Fe

7. Which pair of metal and non-metal is found in liquid state in room temperature:-

(a) Na and C

(b) Hg and F

(d) Hg and Br

8. Although metal form basic oxide, which of the following metal form an amphoteric

oxide?

(a) Na

(b) Ca

(d)Mg

9. An amalgam contains one of the metal as:-

(a) Aluminium

(b) Zinc

(d) Tin

10. A:- Hydrogen gas is not evolved when metal react with nitric acid.

R:- Nitric acid is a strong oxidizing agent.

a) Both A and R are true and R is the correct explanation of A.

(b) Both A and R are true but R is not the correct explanation of A.

(d) A is false , R is true

11. Which of the following are not ionic compounds ?

(i)KCl (ii)HCl (iii)CCl4 (iv)NaCl

(a) (i) and (ii) (b) (ii) and (iii)

12. Silver articles become black on prolonged exposure to air. This is due to the formation of

(a)Ag3N (b) Ag2O

13. Galvanisation is a method of protecting iron from rusting by coating with a thin layer of

(a)Galium (b) Aluminium

14. An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open

in air. It reacts vigorously with water. Identify the element from the following

(a)Mg (b)Na

(c)P (d)Ca

15. Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following

alloys contain non-metal as one of its constituents ?

(a)Brass (b) Bronze

16. Which among the following alloys contain mercury as one of its constituents ?

(a)Stainless steel (b) alnico

17. Reaction between X and Y forms compound Z. X loses electron and Y gains electron. Which of the

following properties is not shown by Z ?

(a)Has high melting point

(b) Has low melting point

(d) Occurs as solid

18. The electronic configurations of three elements X, Y and Z are X – 2, 8; Y – 2, 8, 7 and Z – 2, 8, 2.

Which of the following is correct ?

(a)X is a metal (b) Y is a metal

(d) Y is a non-metal and Z is a metal

19. Although metals form basic oxides, which of the following metals form an amphoteric oxide ?

(a)Na (b) Ca (c) Al (d) Cu

20. Which of the following non-metals is a liquid ?

(a)Carbon (b) Bromine (c) Phosphorus (d) Sulphur

21. Which property of solder makes it suitable for welding electrical wires?

A. Conducting

B. low melting point

C. ductility

D. high melting point

22. Steel is an alloy of iron and carbon with improved strength and fracture resistance compared to other

forms of iron. Many other elements may be present or added. Stainless steels, which are resistant

to corrosion and oxidation, typically need an additional 11% chromium. Because of its high tensile

strength and low cost, steel is used in buildings, infrastructure, tools, ships, trains, cars, bicycles,

machines, electrical appliances, furniture, and weapons. Generally, alloys are a homogeneous

mixture of a metal with a metal or nonmetal. Which among the following alloys contain non-metal?

A. Amalgam

B. Bronze

C. Steel

D. Brass

23. Given bellow are images of gold ore and iron ore. Explain why gold ore is looking very similar to

pure gold but iron ores do not.

24. Roasting of zinc ore is correctly represented by which of the following reaction equation

A. 2 ZnS + O2 → 2 ZnO + 2 SO2

B. 2 ZnS + 3 O2 → 2 ZnO + 2 SO2

C. ZnS + 3 O2 → 2 ZnO + 2 SO2

D. 2 ZnS + 3 O2 → 2 ZnO + SO2

25. The electronic configuration of sodium ion is

(A) 2,8,8

(B) 2,8,2.

(D) 2,8.

26. An element is a pure substance made up of same kind of atoms. At present, nearly 118 elements are

known but all of them do not occur free in nature, some of them have been synthesized by artificial

methods. Based on their properties, they are mainly classified as metals and non-metals. Metals are

those elements which lose electrons and form positive ions i.e., they are electropositive in nature.

They are generally hard, good conductors of heat and electricity, malleable, ductile and have striking

lustre. They have a significant role to play in our daily life. Metals which are of vital importance to

the national defense, energy and industry sector are called strategic metals.

Which of the following is a strategic metal?

(A) Titanium

(B) Zirconium

(D) All of these

27. An element is a pure substance made up of same kind of atoms. At present, nearly 118 elements are

known but all of them do not occur free in nature, some of them have been synthesized by artificial

methods. Based on their properties, they are mainly classified as metals and non-metals. Metals are

those elements which lose electrons and form positive ions i.e., they are electropositive in nature.

They are generally hard, good conductors of heat and electricity, malleable, ductile and have striking

lustre. They have a significant role to play in our daily life. Metals which are of vital importance to

the national defence, energy and industry sector are called strategic metals.

Identify the correct statement(s).

(I) (I) The wires that carry current in our homes have a coating of PVC or a rubber like material.

(II) School bells are made of metals.

(III) Metals do not conduct electricity.

(IV) Metals which produce a sound on striking a hard surface are said to be non-sonorous.

(A) (I) and (III)

(B) (I) and (II)

(D) Only (II)

28. Which one of the following figures describes electrolytic refining:

29. The method of zone refining of metals is based upon the principle of

A. greater solubility of the impurity in molten state than in solid

B. greater mobility of pure metal than impurity

C. higher melting point of impurity than that of pure metal.

D. greater noble character of solid metal than that of the impurity

30. Element X reacts with element Y to form a compound Z. During the formation of compound Z,

atoms of X lose one electron each whereas atoms of Y gain one electron each. Which of the

following properties is not shown by compound Z?

A. High melting point

B. Low melting point

C. Occurrence as solid

D. Conduction of electricity in molten state

31. A cable manufacturing unit tested few elements on the basis of their physical properties

Properties W X Y Z

Malleable Yes No No No

Ductile Yes NO No Yes

Electrical

conductivity

Yes Yes Yes No

Melting Point High Low Low High

Among the above elements, the company would discard the elements for making cables

A) W, X,Y B) X,Y,Z C)W,X,Z D)W,Y,Z

32. The diagram shows the reaction between metal and dilute acid

What is the reason for different behaviour of Mg in test tube B

a)Mg is lighter element than dil. HCl

b) Mg reacts with dil. HCl to produce N2 gas, which helps in floating

c)Mg reacts with dil. HCl to produce H2 gas , which helps in floating

d) Mg reacts with dil. HCl to produce CO2 gas , which helps in floating

33. A student adds some metallic ash in water taken in a test tube. The ash gets completely dissolved in

water and the solution changes colour. What should the student do to test the chemical properties of

the product formed?

a)Test the acidity using blue litmus paper

b) Evaporate the solution to get crystals.

c)Measure the temperature change using a thermometer.

d) Test the basicity by using red litmus paper.

34.

Observe the above activity and mention correct reason for the deposition of brown substance over

iron nail.

a)Iron is less reactive than copper and doesn’t displace copper from its salt solution

b) Iron is more reactive than copper and displaces copper from its salt solution

c)Both iron and copper displace each other from salt solutions

d)None of these are correct

35. The list of metals in the metal reactivity series is given below. In this series along with metal

hydrogen is also placed which is a non metal. The correct reason for placing hydrogen in the series is

a)It is a lighter gas

b)It shows the behaviour of electropositive elements to form H+

ion

c)It is a non reactive element

d)It is very reactive element

36. The correct combination of stainless steel is

a) Fe + C

b) Fe + C + Cr

c) Fe + C + Cr + Ni

d) Fe + C + Mn + Ni

37. The correct statement about the reaction

ZnO + C → Zn+CO is

a)ZnO is being oxidized

b) COis being oxidized

c) ZnO is being reduced

d)Zn is being oxidised

38. Roasting and calcination both the processes are used to obtain oxides of the metal , roasting is done

for the sulphide ore and calcination is done for carbonate ore, these process are done for the

metals______

a)middle in the activity series

B) high in the activity series

C) low in the activity series

d)For all category of metals

39. During the formation of an ionic compound Mg3N2, the cation and anion ion formed are:

a)Mg3+, N2-

b)Mg+

, N3-

c) Mg2+, N2

d)Mg2+, N3-

40. Metals can be given shapes according to our needs , choose the correct option due to which

property/properties they can be given different shapes

a) they are malleable and ductile

b) they are sonorous

c)they are generally hard

d) they have shining surface

41. Roasting of zinc ore is correctly represented by which of the following reaction equation

E. 2 ZnS + O2 → 2 ZnO + 2 SO2

F. 2 ZnS + 3 O2 → 2 ZnO + 2 SO2

G. ZnS + 3 O2 → 2 ZnO + 2 SO2

H. 2 ZnS + 3 O2 → 2 ZnO + SO2

42. Give an Example of a metal which is a liquid at room temperature

(i) iron (ii) Copper (iii) Mercury (iv) Manganese

43. Which is the best Conductor of heat

(i)Silver (ii) Bronze (iii) Aluminum (iv) Copper

44. Which property of solder makes it suitable for welding electrical wires?

A. Conducting

B. low melting point

C. ductility

D. high melting point

45. A student adds some metallic ash in water taken in a test tube. The ash gets completely dissolved in

water and the solution changes colour. What should the student do to test the chemical properties of

the product formed?

a)Test the acidity using blue litmus paper

b) Evaporate the solution to get crystals.

c)Measure the temperature change using a thermometer.

d) Test the basicity by using red litmus paper.

46. Which one of the following is a good conductor of electricity?

(i)Silver (ii)Wood (iii) Glass (iv) Plastic

47. Which metal burnt easily

(i)Iron (ii) Coal (iii) Alkali (iv) Silver

48. Metals can be given shapes according to our needs , choose the correct option due to which

property/properties they can be given different shapes

a) they are malleable and ductile

b) they are sonorous

c)they are generally hard

d) they have shining surface

49. When metal (M)is treated with diluted H2SO4, a gas is evolved and is collected over the

water as shown in the figure

The correct conclusion is

a)The gas evolved is Hydrogen.

b)The evolved gas is lighter than air.

c)The evolved gas is SO2.

d)Both (a) and (b).

50. Identify gas A in in the given experiment

a) Nitrogen b)Hydrogen c)Oxygen d)Carbon dioxide

51. The diagram shows the reaction between metal and dil. acid

Reason for different behavior of Mg in test tube B

a)Mg is lighter element than dil. HCl

b)Mg reacts with dil. HCl to produce H2 gas which helps in floating.

c) Mg reacts with dil. HCl to produce N2 gas which helps in floating.

d) Mg reacts with dil. HCl to produce CO2 gas which helps in floating.

52. The metal which does not react with cold or hot water is

a)Sodium b)Calcium c)Magnesium d)Gold

53. Which of the following metals are stored in kerosene?

a)sodium and potassium

b)sodium and copper

c)potassium and mercury

d)sodium and mercury

54. Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion:Gold,Silver, Platinum are found in free state.

Reason: The metals at the bottom of the activity series are least reactive.

Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not the correct explanation of A.

(c)A is true but R is false.

(d) A is false but R is true.

55. Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion:Food cans are coated with tin and not with zinc.

Reason: Zinc is more reactive than tin.

Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not the correct explanation of A.

(c)A is true but R is false.

(d) A is false but R is true.

56. Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion:Different metals have different reactivities with water and dilute acids.

Reason: Reactivity of a metal depends on it position in the reactivity series.

Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not the correct explanation of A.

(c)A is true but R is false.

(d) A is false but R is true.

57. Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion:A mineral is called ore,when metal can be profitably extracted from it.

Reason: All ores are minerals but all minerals are not ores.

Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not the correct explanation of A.

(c)A is true but R is false.

(d) A is false but R is true.

58. Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion:Iron is found in free state in nature.

Reason: Iron is a highly reactive metal.

Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not the correct explanation of A.

(c)A is true but R is false.

(d) A is false but R is true.

59. Galvanization means

a. Coating with tin

b. Coating with zinc

c. Alloys making

d. None of these

60. Write Some characteristics of chemical reaction

a. Change in colour

b. Change in temperature

c. Evolution of gas & formation of ppt

d. All of these

61. C6H12O6 + 6O2—-------------------------6CO2 + 6 H2O

The above reaction is a /an

a. Displacement reaction b . Endothermic reaction

b. C. Exothermic reaction d. Neutralization reac6

62.

Metals have_______ melting and boiling points.

a.High

b. Low

c. Both

d. Allof these

63. The ability of metals to be drawn into thin wires is known as

a.ductility

b. malleability

c. Sonority

d. Conductivity

64.

Due to its semiconductor properties the Non-metal used in T.V. is

a.carbon

b. Silicon

c. Bromine

d. Fluroine

65. Generally Non-metals are not conductors of electricity. Which of the following is a good

conductor of electricity?

a.diamond

b. Graphite

c. Sulphur

d. Fullerene

66. Iodine is a

a.non-metal

b.metal

c.metalloid

d.none

67. The ability of metals to be drawn into thin wire is known as

a. Ductility

b. Malleability

c. Sonorous

d. Conductivity

68. Which among the following metals has the lowest melting point?

a. Lithium

b. Sodium

c. Magnesium

d. Mercury

69.

70.

71.

72.

73.

74.

75.

76.

77.

78.

79.

80.

81.

VSA 2 MARKS EACH

1. Give Two examples of metals that are good conductor and poor conductor of heat and

electricity

2. Compound X and Aluminium are used to join the railway tracks. Identify the X and

name this reaction.

3. These group of metals are refined by electrolytic refining?

(a)Au &Cu

(b) Na & K

(d) Cu & Na

4. Compound X and aluminium are used to join railway tracks. (a) Identify the compound X (b) Name

the reaction (c) Write down its reaction.

5. A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is

toxic whereas C causes global warming

(a) Identify A, B and C

(b) To which group of periodic table does A belong ?

6. An element A reacts with water to form a compound B which is used in white washing. The

compound B on heating forms an oxide C which on treatment with water gives back B. Identify A, B

and C and give the reactions involved.

7. Anodising is an electrolytic process for producing thick oxide coatings,

usually on aluminium and its alloys. The oxide layer is typically 5 to 30μm

in thickness and is used to give improved surface resistance to wear and

corrosion, or as a decorative layer. If H2SO4 solutionis used as electrolyte then

answer the following.

I. The aluminium is placed at which electrode during electrolysis.

A. Cathode

B. Anode

C. It can be placed at both electrodes

D. Not as electrode

II. Why gold and silvers are not coloured or anodized?

A. Expensive to colour or anodize

B. These are very brittle so can brake during the process

C. The keep the beauty of the metal surface

D. Are least reactive metals

8. We kept a solution of CuSO4 in an iron pot. After a few days, the iron pot was found to have several

holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.

9. Suggest the possible reason behind formation of sodium hydroxide and only aluminium oxide when

both sodium and aluminium react with water.

10. Waheeda dissolved some common salts in the given experimental set up and found that the bulb is

glowing while she performed same experiment by taking the solid common salts, she marked that the

bulb is not glowing.

Analyse both the experiments and mention the reason for difference in results.

11. Astudent has been collecting silver coins and copper coins. One day she observed a black coating on

silver coin and green coating on copper. Mention the reason for such change. Name the substances

formed in both cases.

12. Riya a student of class 10 was given sample of Mg, Zn, Fe, and Cu and dilute

HCl and Dilute HNO3. She put each sample of metals in the test tube containing dilute HCl and Dilute

HNO3 separately. Basing on her observation she had drawn the following observation.

1-Bubbles are formed when Mg is put in the test tube containing dilute HNO3

2-Bubble are seen when Zn is put in the test tube containing dilute HCl.

3- Bubbles are released from the test tube when Cu metal is put in the test tube containing dilute HCl.

4- Bubbles are formed when Fe is put in the test tube containing dilute HNO3

Analyse the inferences drawn by Riya and identify the incorrect statements.

13. A student has been collecting silver coins and copper coins. One day she observed a black coating on

silver coin and green coating on copper. Mention the reason for such change. Name the substances

formed in both cases.

14. We kept a solution of CuSO4 in an iron pot. After a few days, the iron pot was found to have several

holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.

15. Why ionic compounds have high melting point?

16. An element reacts with air (oxygen)to form its oxide.When dissolved in water, the solution

turns red litmus blue.Is it a metal or a non metal? Justify your answer.

17. Iqbal treated a lustrous, divalent element M with sodium hydroxide.He observed the

formation of bubbles in the reaction mixture. He made the same observations when this

element was treated with hydrochloric acid.Suggest the way he can identify the produced

gas.

18. A yellow coloured powder ‘X’ is soluble in carbon disulfide. It burns with a blue flame forming

suffocating smelling gas which turns moist blue litmus red. Identify ‘X’ and give chemical

reaction.

19. 24 Carat gold is not suitable for making jewellery. Why?

20. Write Some alloys.(any four)

21. What happens when nitric acid is added to an egg-shell?Justify your answer.

22.

23.

SA 3 MARKS EACH

1. An element A react with water to form a compound B used in whitewashing. The B

on heating Forms an oxide C which gives back B on treating with water. Identify A,B

and C.

2. Arun uses a copper vessel at his home. After some time he found it is coated with

green colour.

(a) What is the chemical composition of this green coating?

(b)Why do copper vessel forms such a green coating?

(c)Name the Phenomenon, responsible for green coating?

Study the above graph and answer the following:-

(i) Which of the following is represented by Y.

(a) Al (b) Mg (c) Zn (d) Cant be predicted

(ii) What will be observed if Mg ribbon is placed in CuSO4 solution?

(a) Solution turns blue.

(b) Solution turns colourless from blue.

(d) Solution turns Red.

(iii) Which one will be represented by X

(a) Na (b) Mg (c) Al (d) Zn

4. A student has been collecting silver coins and copper coins. One day, she observed a black coating

on silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for

these coatings ? Write the chemical name of black and green coatings.

5. A metal ‘M’ has the electronic configuration 2, 8, 3 and occurs in nature as M2O3. It is more reactive

than Zinc. Answer the following questions :

(a) Name the metal ‘M’

(b) Name the ore from which this metal is extracted.

6. Give reasons for the following observations:

(i) Copper vessels get a green coat when left exposed to air in the rainy season.

(ii) Metal sulphides occur mainly in rocks but metal halides occur mostly in sea and lake

waters.

7. An element A burns with golden flame in the air. It reacts with another element B, atomic number

17, to give a product C. An aqueous solution of product C on electrolysis gives a compound D and

liberates hydrogen. Identify A, B, C and D. Also, write down the equations for the reactions

involved.

8. When a metal X is treated with cold water, it gives a basic salt Y with the molecular formula XOH

(Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also

write the reaction involved.

9. Ionic compound is a chemical compound in which ions are held together by ionic bonds. An ionic

bond is the type of chemical bond in which two oppositely charged ions are held through electrostatic

forces. We know that, metal atoms have loosely bound valence electrons in their valence shell and

non-metal atoms need electrons in their valence shell to attain noble gas configuration. The metal

atom loses the valence electrons while non-metal atom accepts these electrons. By losing electrons,

metal atoms change to cations and by accepting electrons, non-metals form anions. Ionic compounds

are generally solid and exist in the form of crystal. They have high melting and boiling points.

Why we cannot melt salt by heating over gas flame but make syrup easily by melting sugar. Write

the chemical name and draw the electron dot structure of common salt.

10. The reaction of metallic oxides of zinc, magnesium and copper with the following metals are given

below

Metal Zinc Magnesium Copper

Zinc oxide

Magnesium

oxide

Copper oxide

Complete the above table by writing YES in the cases the displacement reactions taking place

11. The electronic configuration of two elements X and Y are given below

X:2,7 Y: 2,8,1

a)Show the formation of bond between X and Y by electron transfer.

b) Mention the type of bond formed between X and Y.

c) This compound is having high melting and boiling point. Suggest one reason for this.

12. A teacher asks students to identify a metal, M.She gives them the following clues to help them.

I)Its oxide reacts with both HCl and NaOH.

II)It does not react with hot or cold water but reacts with steam.

III)It can be extracted by electrolysis of its ore.

Basing on the clues

a) Identify the metal M.

b) List the chemical equations of the reaction of the oxide of the metal M with HCl and NaOH.

c) Mention the type of oxide into which the oxide of metal M can be categorized.

13. When a metal X is treated with cold water, it gives a basic salt Y with the molecular formula XOH

(Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also

write the reaction involved.

14. Two ores A and B were taken. On heating, ore A gives CO, whereas ore B gives SO2. What steps

will you take to convert them into metals?

Two ores A and B were taken. On heating, ore A gives CO, whereas ore B gives SO2. What steps

will you take to convert them into metals?

15. What is cinnabar? How is metal extracted from cinnabar? Explain briefly?

16. Ashish was given Mg, Zn, Fe and Cu metals. He puts each of them in dil. HCl contained in

different test tubes. Identify which of them

i)will not displace H2 from dil. HCl

ii)forms a pale green substance

iii)will be displaced from its salt solution by all other metals.

17. Shilpa took a metal X which generally turns black when kept in open for several days. The

metal when rubbed with toothpaste again starts shining.

a) Identify the metal X.

b) Why do the metal X turns black.Name the phenomenon involved.

c) Name the black substance formed and write its formula.

18.

i)Identify the gases evolved at the anode and cathode in the above experimental set up.

ii)Name the process that occurs.Why is it called so ?

iii)Illustrate the reaction of the process with the help of a chemical reaction.

State some conditions for the rusting of iron.

19 Give scientific reason

Platinum , Gold &silver are used for making jewellery.

20 A metal is treated with dil.H2SO4.The gas evolved is collected by the method . Answer the

following

1.write the method of collection of the gas.

2. Name the gas.

3. Is the gas soluble or insoluble in water?

CASE BASED QUESTIONS 4 MARKS

1. The chemical reactivity of an element depends upon its electronic configuration.

During chemical reaction , atoms of all elements tend to achieve a complete filled

valance shell. Metals tend to lose one or more electron while non-metal tend to gain

one or more electron. The compound form by transfer of electron from one element

to other is called ionic compound. The electronic configuration of three elements

are:-

X- 2,8,1

Y- 2,8,7

Z- 2,8,2

Answer the following:-

(a) Which of the following is correct regarding these element:-(i) X is non metal (ii)

Y is metal (iii) both i)and ii) (iv) Y is non metal and Z is metal.

(b) If X react With Y then which type of bond is formed between them:-

(i) Hydrogen bond (ii) Covalent bond (iii) Ionic bond (iv) None of the above.

(i) X (ii) Y (iii) Z (iv) both X and Z

(d) The compound formed by the combination of X and Y is :-

(i) Good conductor of electricity in solid state.

(ii) Good conductor of electricity in molten state.

(iii) Good conductor of electricity in any state.

(iv) Bad conductor of electricity in any state.

2. Metals have been arranged according to their reactivity series. Most reactive metals

are found in combined state in nature whereas less reactive metals are found in free

state. The general method of extraction of metal is specific for different type of

metals.

(a) Copper pyrites contains

(i) Cu2O (ii) Cu2S (iii) CuFeS2 (d) CuCO3

(b) Roasting is the process in which

(i) Air is necessary

(ii) Air is not necessary

(iii) Air May not be necessary.

(iv) None of the above.

(i) C (ii) Al (iii) Either of these (iv) none

(d) After electrolytic refining the pure metal deposited on:-

(i) Anode (ii) Cathode (c)May be cathode or anode (d) At the bottom of

electrolytic tank.

3. Give reasons for the following:

(i)Why Hydrogen gas is not evolved when most of the metals react with nitric acid

(ii) Tarnished copper vessels are cleaned with tamarind juice.

(iii) Aluminium is more reactive than iron yet there is less corrosion of aluminium as compared to

iron when both are exposed to air.

(iv) ) Aluminium is a reactive metal but is still used for packing food articles. Give reasons.

(a) You are provided with coal,wood and iron.Which item should be selected for making school bell

and why?

(b) Why electric wires are made up of copper?

c). By the transfer of electrons, illustrate the formation of bond in magnesium chloride and identify

the ions present in this compound.

(d) Name two metals which do not react with water.

5. A non-metal A, the largest constituent of air, when heated with H2 in a 1:3 ratio in the presence of a

catalyst (Fe), gives a gas B. On heating with Oz, it gives an oxide C. If this oxide is passed into the

water in the presence of air, it gives an acid D which acts as a strong oxidising agent.

(a) Identify A, B, C, and D

(b) To which group of periodic tables does this non-metal belong?

6. Silver articles become black after some time when exposed to air.

This is because it reacts with sulphur in the air to form a coating

of silver sulphide. Copper reacts with moist carbon dioxide in the

air and slowly loses its shiny brown surface and gains a green

coat. This green substance is copper carbonate. Iron when exposed

to moist air for a long time acquires a coating of a brown flaky substance called

rust. Let us find out the conditions under which iron rusts.

i) Write a chemical reaction occur during the rusting of iron.

ii) Give three methods to prevent the corrosion of metals.

iii) What do you meant by the alloy? Give one example.

iv) can you name the process where zinc is deposited over reactive metals?

7. Refining is the process of purification of metals. One of the important method of refining is

electrolysis. In electrolysis, electrical energy is used to bring about non -spontaneous redox reaction.

This is done by the passing of electric current through liquid containing ions, known as electrolyte. In

contrast to metals, the current in electrolytes is carried by the movement of ions rather than

movement of electrons. The solid conductors inserted into liquid are called electrodes, the one with

positive charge is called anode and the one with negative charge is called cathode.

1-Mention the name of two metals whose refining is done by using the process of electrolysis.

2-Distinguish between electrolytic reduction and electrolytic refining

3-What is meant by anode mud? Name the electrode where the pure metal gets deposited during

electrolytic refining.

8. Reena immersed a zinc plate in an aqueous solution of copper sulphate.She noticed a thick layer of

copper on the surface of the zinc plate after an hour.

1-State the reason of the formation of the colourless solution. Also mention the chemical formula of

the colourless solution.

2-What should Reena have done to make the reaction faster?

3-No reaction takes place when a copper plate immersed in an aqueous solution of zinc sulphate.

Explain the reason behind this.

9. Harshita performed an experiment to study about thermal conductivity in metals.She took a

stand and fix an aluminium or copper rod with the help of clamp.Fix a pin to the free end of

rod with the help of wax.On heating the rod near the place it is clamped, the wax melts and

pin falls down but metal does not melt.

i)What do you came to know about metals in this experiment?

ii)What do you mean by thermal conductivity?Give some examples of thermal conductors.

iii)Aluminium metal does not melt in the given experiment.Give reason and give two uses of

aluminium.

10. A metal ‘X’ combines with a non-metal ‘Y’ by the transfer of electrons to form a compound

‘Z’.

i)State the type of bond in compound ‘Z’.

ii)What can you say about the melting and boiling point of compound Z.

iii)Will this compound dissolve in kerosene or petrol?

iv)Will this compound be a good conductor of electricity?

11. Write scientific reason for the following

1.Gold jewellery retain their lustre even after several years of use.

2. Iron grills are frequently painted.

12. Write physical properties of metals and Non-metals.(any four)

13.

14.

15.

16.

LA ( 5MARKS)

1 The ability of an atom to donate electrons and form positive ion (cation) is known as

electro-negativityor metallic character. Down the group, metallic character increases

due to increase in atomic size and across the period, fromleft to right electro-positivity

decreases due to decrease in atomic size.Non-Metallic Character The ability of an

atom to accept electrons to form a negative ion (anion) is called non-metallic character

or electronegativity. The elements having high electro-negativity have a higher

tendency to gain electrons and form anion. Down the group, electronegativity

decreases due to increase in atomic size and across the period, from left to right

electronegativity increases due to decrease in atomic size.

1. Which of the following correctly represents the decreasing order of metallic

character of Alkali metals plotted in the graph?

a) Cs>Rb>Li>Na>K

b) K>Rb>Li>Na>Cs

c) Cs>Rb>K>Na>Li

d) Cs>K>Rb>Na>Li

2.Hydrogen is placed along with Alkali metals in the modern periodic table though it

shows non-metallic character

a) as Hydrogen has one electron & readily loses electron to form negative ion

b) as Hydrogen can easily lose one electron like alkali metals to form positive ion

c) as Hydrogen can gain one electron easily like Halogens to form negative ion

d)as Hydrogen shows the properties of non-metals.

3.Which of the following has highestelectronegativity? a) F

b) Cl

c) Br

d) I

4. Identify the reason for the gradual change in electronegativity in halogens down

the group.

a) Electronegativity increases down the group due to decrease in atomic size

b) Electronegativity decreases down the group due to decrease in tendency to lose

electrons

c) Electronegativity decreases down the group due to increase in atomic radius/

tendency to gain electron decreases

d) Electronegativity increases down the group due to increase in forces of attractions

between nucleus & valence electrons.

5. The process of depositing Zn layer on iron article is called:-

(a) Crystalisation

(b) Sublimation

(d) Centralisation.

2 A metal (E) is stored under kerosene. When a small piece of it is left open in the air, it catches fire.

When the product formed is dissolved in water, it turns red litmus to blue.

(i) Name the metal (E).

(ii) Write the chemical equation for the reaction when it is exposed to air and when the product is

dissolved in water.

(iii) Explain the process by which the metal is obtained from its molten chloride.

3 Ores mined from the earth are usually contaminated with large amounts of impurities such as soil,

sand, etc., called gangue. The impurities must be removed from the ore prior to the extraction of the

metal. The processes Several steps are involved in the extraction of pure metal from ores. Metals and

Non-metals used for removing the gangue from the ore are based on the differences between the

physical or chemical properties of the gangue and the ore. Different separation techniques are

accordingly employed.

I.What are the process for the extraction of metals of low reactivity series?

II. What is meant by Roasting?

III. Give one example of extracting metals low in the activity series.

IV. What is the another name for HgS an ore of mercury?

V. In which form does metals of low activity series occur in the earth crust?

4 A metal ‘M’ is stored under kerosene . It vigorously catches fire, if small piece of this metal is kept

open in air. Dissolution of this metal in water releases great amount of energy and the metal catches

fire. The solution so formed turns red litmus to blue.

a)Name the metal.

b)Why is metal ‘M’ stored under kerosene?

c)Write the formula of the compound formed when this metal is exposed to air. Show the formation

of this compound by transfer of electron.

d) If the hydroxide of this metal reacts with hydrochloric acid what would be the products formed?

Give a name to this type of reaction

5 Silver articles become black after some time when exposed to air.This is because it reacts

with sulphurin the air to form a coating of silver sulphide.

Copper reacts with moist carbon dioxide in the air and slowly loses its shiny brown surface

and gains a green coat.This green substance is copper carbonate.

Iron when exposed to moist air for a long time acquires a coating of a brown flaky

substance called rust.

i)Write a chemical reaction occur during the rusting of iron.

ii)Give three methods to prevent the corrosion of metals.

iii)What do you mean by the alloy?Give one example.

iv)What is meant by Galvanization?

v)What is Amalgam?

6 In the formation of compound between two atoms A &B .A loses two electrons & B gains

one electron.

I. Name the nature of bond between A & B

2. Common salt conducts electricity only in the molten state. Why?

3. Why is melting point of NaCl high?

ANSWERS FOR MCQs

1. a. Calcium

2. a

3. b

4. C. ZnSO4

5. b. Use pieces of Zn flakes

6. b. Cu

7. d. Hg and Br

8. C. Al

9. c. Mercury

10. a

11. (b)

12. (c)

13. (c)

14. (b)

15. (d)

16. (d)

17. (b)

18. (d)

19. (c)

20. (b)

21. (A). low melting point

22. (C)) STEEL

23. Gold is the least reactive among all the metals due to which it is found in almost pure form but due to

reactive nature of iron ores are found in the form of iron oxides, sand and clay referred to as gangue.

24. (B). 2 ZnS + 3 O2 → 2 ZnO + 2 SO2

25. (D) 2,8

26. (D) All of these

27. (B) (I) and (II)

28. figure a

29. A. greater solubility of the impurity in molten state than in solid

30. B. Low melting point

31. B

32. C

33. D

34. B

35. B

36. C

37. C

38. A

39. D

40. A

41. (B). 2 ZnS + 3 O2 → 2 ZnO + 2 SO2

42. Mercury

43. Silver

44. (A). low melting point

45. d) Test the basicity by using red litmus paper.

46. Silver

47. Alkali

48. a) they are malleable and ductile

49. d

50. b

51. b

52. b

53. a

54. a

55. a

56. a

57. b

58. d

59. c

60. d

61. c

62. a

63. a

64. b

65. b

66. a

67. a

68. d

69.

70.

71.

ANSWERS FOR VSA ( 2 MARKS)

1 Good conductor- Iron and copper ; poor conductor- lead and mercury.

2 Fe2O3 ; Thermite reaction

3 B Na & K

4 (a)Compound X must be iron (III) oxide, Fe2O3.

(b)The reaction is known as ‘thermite reaction’.

(c)The reaction is carried out by igniting the mixture with a Mg-ribbon.

Fe2O3(s) + 2Al(s) ⟶

ignited

2Fe(l) + Al2O3(s)

Iron (III) oxide Aluminium iron(melt) Aluminium oxide

5 The non-metal A must be carbon, as carbohydrates, proteins etc, all contain carbon. It forms two

oxides : CO (carbon monoxide) and CO2 (carbon dioxide). As CO is toxic, hence B is CO. As CO2

causes global warming, C is CO2.

(a)A = carbon, B = carbon monoxide (CO), C = carbon dioxide (CO2)

(b)Carbon (A) belongs to group 14 of the periodic table.

Ca + H2O ⟶ Ca(OH)2 ⟶

Heat

CaO + H2O

Calcium Calcium hydroxide Calcium oxide

(A) (B) (C)

+H2O

7 . I. B. Anod, II. D. Are least reactive metals

8 Iron is more reactive than copper. Due to this, iron displaced copper from copper sulphate to form

iron sulphate. A portion of the iron pot got dissolved, causing holes in it.

CuSO4 + Fe → FeSO4 + Cu

9 Sodium is more reactive than aluminium and when put in water forms sodium oxide which further

dissolves in water to give sodium hydroxide solution whereas aluminium reacts with oxygen to form

aluminium oxide which further do not dissolve in water

10 Ionic compound does not conduct electricity in solid state but they do so in fused state as in fused

state free ions are available

11 Reason: Corrosion of metals on exposer to air and moisture

Silver: Silver sulphide(Black)

Copper: Copper carbonate+ Copper hydroxide(Green)

12 Statements 3 and 4 are incorrect

13 Reason: Corrosion of metals on exposer to air and moisture

Silver: Silver sulphide(Black)

Copper: Copper carbonate+ Copper hydroxide(Green)

14 Iron is more reactive than copper. Due to this, iron displaced copper from copper sulphate to form

iron sulphate. A portion of the iron pot got dissolved, causing holes in it.CuSO4 + Fe → FeSO4 + Cu

15 Strong Electrostatic Forces: Ionic compounds have strong attractions between oppositely charged

ions due to electrostatic forces.

Lattice Structure: Ions are arranged in a repeating 3D lattice, requiring substantial energy to break the

structure.

Heat Energy Absorption: High energy input is needed to overcome electrostatic forces, resulting in

high melting points.

16 Basic oxide turns red litmus blue,so it is a metallic oxide.It is a metal.eg: Na2O + H2O →

2NaOH

17 The gas which is liberated is H2 gas.To check the presence of H2 gas,we can bring a

burning matchstick near the evolved gas, if the matchstick burns with a pop sound; it

confirms the evolution of H2 gas.

Reaction with metal: M + 2NaOH→ Na2MO2 + H2 Reaction with HCl: M+ 2HCl→ MCl2

+H2

18 ‘X’ is sulphur. S+O2→ SO2, it is non metal.

19 It is very soft and alloyed with either silver or copper to make it hard.

20 1.stainless steel (Fe, Ni,cr)

2. Brass ( cu & Zn)

3.Bronze( tin & copper)

4.solder( tin & lead)

21 CO2 gas is evolved.

Egg shell contains CaCO3 which on reactions with HNO3 release CO2.

ANSWERS FOR SA ( 3 MARKS)

1. A, calcium; B calcium hydroxide; C Calcium oxide.

2. (a)Basic copper carbonate CuCo3.Cu(OH)2; (b) When it react with atmospheric Oxygen and CO2; (c)

Corrosion

3. (i) a (ii) B (iii) a

4. The name of the phenomenon is corrosion. The chemical name of black coating is silver sulphide

(Ag2S) formed due to attack of H2S gas present in the atmosphere on silver and that of green coating

is basic copper carbonate formed due to attack of moist air (CO2, O2 and H2O vapours) on copper.

2 Ag(s) + H2S(g) ⟶ Ag2S(s) + H2(g)

Silver Hydrogen sulphide Silver sulphide Hydrogen

(From air) (Black)

2 Cu (s) + CO2(g) + O2 (g) + H2O (l) ⟶ CuCO3.Cu(OH)2

Copper From moist air Basic copper carbonate

(Green)

5. (a)Metal ‘M’ is Aluminium.

(b)Ore from which Al is extracted is Bauxite (Al2O3.2H2O)

(c)Bauxite is converted to Al by electrolytic reduction

6. (i)Copper vessels react with CO2, O2 and moisture to form green-coloured basic copper carbonate

[CuCO3.Cu(OH)2].

(ii)It is because sea water contains sodium chloride due to which metal halides are formed, whereas

sulphur is found below rocks. Therefore, metal sulphides are formed in rocks.

7. Sodium is more reactive than aluminium and when put in water forms sodium oxide which further

dissolves in water to give sodium hydroxide solution whereas aluminium reacts with oxygen to form

aluminium oxide which further do not dissolve in water

8. Element A is sodium metal (Na) as it burns with a golden flame.

Element B with atomic number 17 is chlorine (Cl).

Sodium and chlorine combine to form sodium chloride, NaCl(compound C).

We can write the reaction as

2 Na + Cl2 → 2 NaCl.

An aqueous solution of NaCl on electrolysis gives the compound D, sodium hydroxide(NaOH). We

can write the reaction as

2 NaCl (aq) + 2 H2O (l) → 2 NaOH (aq) + Cl2 (g) + H2 (g)

9. X is Na because the molecular mass of NaOH is 40.

Na (23) + O (16) → NaOH (40)

Hence,

• X is Sodium.

• Y is Sodium hydroxide.

• Z is hydrogen, which catches fire when it reacts with water.

2 Na + 2 H2O → 2 NaOH + H2.

Here oxygen is losing hydrogens, so it is oxidised. The Na has gained oxygen, so it is reduced.

Therefore, it is a redox reaction and an H2 displacement reaction. Redox reactions are reactions in

which one species is reduced and another is oxidised. Consequently, the oxidation state of the species

involved must change.

10. Metal Zinc Magnesium Copper

Zinc oxide No Yes No

Magnesium

oxide

No No No

Copper oxide Yes Yes NO

11. a)Y+

b)Ionic bond

c)Soluble in polar solvent like water/ Has high MP/BP

12. a) Metal M is Aluminium

b) Al2O3+6HCl→2AlCl3 +3H2O

Al2O3+2NaOH→2NaAlO2 +H2O

c) Amphoteric oxide

13. X is Na because the molecular mass of NaOH is 40.

Na (23) + O (16) → NaOH (40)

Hence,

• X is Sodium.

• Y is Sodium hydroxide.

• Z is hydrogen, which catches fire when it reacts with water.

2 Na + 2 H2O → 2 NaOH + H2.

Here oxygen is losing hydrogens, so it is oxidised. The Na has gained oxygen, so it is reduced.

Therefore, it is a redox reaction and an H2 displacement reaction. Redox reactions are reactions in

which one species is reduced and another is oxidised. Consequently, the oxidation state of the species

involved must change.

16. The molecules of Salt are held by strong ionic bond whereas sugar is a covalent molecule.

Sodium chloride.

14. A carbonate ore is calcinated to obtain the oxide of the metal. When a carbonate ore is heated, we get

carbon dioxide. The following equation shows the calcination of zinc carbonate.

ZnCO3 → ZnO + CO2

When a sulphide ore is roasted, we get Sulphur dioxide. Zinc sulphide is roasted to obtain zinc oxide.

2 ZnS + 3 O2 → 2 ZnO + 2 SO2.

After any of the above steps, zinc oxide is reduced to obtain pure zinc.

ZnO + C → Zn + CO

15. Cinnabar is mercury sulfide (HgS), a bright red mineral. Metal Extraction: Cinnabar is heated,

releasing mercury vapor; vapor is condensed and purified. Mercury is collected and used in various

applications.

16 i)Cu ii)Fe iii)Cu

17 a) Ag

b) Silver reacts with some sulphur compounds as hydrogen sulphide to form black layer

of silver sulphide.

2Ag +H2S→ Ag2S +H2, the phenomenon is known as corrosion.

c) The black substance formed is silver sulphide and is formula is Ag2S

18 i) Anode: Chlorine gas Cathode: Hydrogen gas

ii) Chlor alkali process.Since the product obtained are alkali, chlorine gas and

hydrogen gas, the process is called chlor alkali process.

19 1.presence of moisture

2. Presence of oxygen

20 They are lustre.

Highly malleable and ductile.

Not combine with O2 in the air even at high temperature.

21 1.downward displacement of water.

2. Hydrogen

3. The gas is insoluble in water. So it can be collected over water.

ANSWERS FOR CBQ ( 4 MARKS)

1. (a) iv; (b) iii (c) iv (d) ii

2. (a) iii (b) i (c) iii (d) ii

3. (i) Hydrogen gas is not evolved when most metals react with nitric acid. It is because HNO3 is a

strong oxidising agent. It oxidises the H2 produced to water and itself gets reduced to any of the

nitrogen oxides (N2O, NO, NO2).

(ii) Tamarind contains acid which reacts with basic copper carbonate and product gets dissolved and

removed from copper vessel.

(iii)Aluminium forms oxide layer on its surface which does not further react with air.

(iv)Aluminium is a strong and cheap metal. It is also a good conductor of heat. But it is highly

reactive. When it is exposed to moist air, its surface is covered with a thin impervious layer of

aluminium oxide (Al2O3). This layer does not allow moist air to come in contact with the fresh metal

and hence, protects the metal underneath from further damage or corrosion. Thus, after the formation

of this protective layer of Al2O3, aluminium becomes resistant to corrosion. It is because of this

reason that although aluminium is a highly reactive metal, it is still used in food packaging.

4. (a)Iron should be selected.It is because metals are sonorous, i.e. they produce sound when struck with

a hard substance.

(b)It is because copper is good conductor of electricity.

(c)

(d)Gold and silver do not react with water.

5. (a) A is nitrogen; because nitrogen is the largest constituent of air. B is ammonia, C is nitrogen

dioxide, and D is nitric acid (a potent oxidising agent).

When nitrogen is heated with hydrogen in the presence of a catalyst, the following reaction occurs.

N2 + 3 H2 → 2 NH3.

When nitrogen is heated with oxygen, we get nitrogen dioxide.

N2 + 2 O2 → 2 NO2

When nitrogen dioxide is treated with water, we get nitric acid.

NO2 + H2O → HNO3

(b) This non-metal belongs to Group 15.

6. i) Fe(s) + O2(g) + H2O(l) Fe2O3. XH2O

ii) Galvanization, painting & oiling, anodizing or making alloys..

iii) An alloy is a homogeneous mixture of two or more metals or a metal and a non- metal.

Eg: Iron is mixed with Nickel and Chromium to give stainless steel.

iv) Galvanization. It is a method of protecting steel and iron from rusting by coating them with a thin

layer of zinc by electricity.

7. 1- Copper &

2- Electrolytic reduction is done in case of the metals high in the activity series and electrolytic

refining is done for purifying metals.

3- During the purification of metal by the process of electrolytic refining the insoluble

impurities deposited at anode is called anode mud.

Pure metal is deposited at cathode

8. 1-Zinc metal displaces copper from copper sulphate solution, ZnSO4

2- Byadding dilute sulphuric acid

3-Copper is less reactive than zinc , hence copper is unable to displace zinc

9. i)The experiment tells that given metals are good conductors of heat.Metals also have high

melting points in most of the cases(as metal wires does not melt on heating).

ii)It is the property due to which metals can conduct heat.eg: Cu, Al, Fe etc are good

conductors of heat.

iii)Aluminiummetal has high melting point,that’s why it does not melt in the given

experiment.

Uses of Al

i)Used in making kitchen utensils.

ii)Used in making window frames.

10. i)Ionic bond in compound ‘Z’.

ii)It has high melting and boiling point due to stronger inter-ionic attraction.

iii)No,as electrovalent compounds are soluble in water but insoluble in kerosene or petrol.

iv)No, as its solution in water contains ions but in solid state do not conduct electricity as

movement of ions is not possible due to its rigid structure.

11. Ans. Noble metal and not affected by air.so gold jewellery retain their lustre even after

several years.

12. Physical properties of metals

1.sonorous

2.Lustrous

3.High melting point

4.High density except Na & K

Physical properties of Non-metals

1.Nonsonorous

2.low melting point

3.low density

4.nonductile and bad conductor of heat.

KEY 5 MARKS

1 1.c 2.b 3 a 4 c 5c

2 ’E’ is sodium which catches fire in presence of moisture.

(ii)4Na + O2

⟶ 2Na2O

Na2O + H2O ⟶ 2NaOH

(iii)Electrolytic reduction: Electric current is passed through molten Nacl. Sodium is formed at

cathode and chlorine gas is liberated at anode.

2NaCl

electrolysis

→ 2Na + Cl2

Molten

3 I. Oxides of these metals are reduced to metal by simply heating.

II. The sulphide ores are converted into oxides by heating strongly in the presence of excess air. This

is called as Roasting.

III. 2Cu2O + 3O2+ heat 2Cu2O(s) + 2SO2(g)

On further heating: 2Cu2O + Cu2S + heat 6 Cu(s) + SO2(g).

IV. HgS is also called as Cinnabar

V. They occur in a free state. Example- Gold

4 1- Na

2- Sodium metal is highly reactive element and it can catch fire on exposure to moisture.

3- Na2O

The product formed would be NaCl , the type of reaction is Neutralization Reaction

5 i) Fe(s) + O2 +H2O(l) → Fe2O3. XH2O

ii) Galvanization, painting and oiling,anodizing or making alloys.

iii) An alloy is a homogeneous mixture of two or more metals or a metal and a non-

metal.

Eg. Iron is mixed with Nickel and Chromium to give stainless steel.

iv) It is a method of protecting steel and iron from rusting by coating them with a thin

layer of zinc.

The alloy which contains mercury as one of the metals is called amalgam.

KVS ZIET BHUBANESWAR

CBTI X SCIENCE CH_4_ CARBON AND ITS COMPOUND

Q. NO QUESTION

MCQ s 1 MARK EACH

1. Name the homologous series to which C3H8 belongs

(a ) Alkynes

(b ) Alkenes

(c ) Alkanes

(d ) Cycloalkanes

2. Identify the functional groups present in the compound-

CH3CH2CH2CH2CHO

3. Interpreteamong the following will conduct electricity?

a) C6H12O6

b) C2H5OH

c) NaCl (aq)

d) C2H6

4. In order to form branching, an organic compound must have a minimum of

a) Four carbon atom

b) three carbon atom

c) Five carbon atom

d) Any number of carbon atom

5. Alcohols can be prepared by the hydration of

a) Alkenes

b) alkynes

c) alkanes

d) acids

6. Which of the following molecules has all its atoms joined together by double covalent bond

a) Methane

b) water

c) carbon dioxide

d) Nitrogen trichloride

7. Suggest the type of fuels :

(a) Burn with a flame?

(b) Burn without a flame?

8. Assertion -The functional group present in alcohol is –OH.

Reason - It is the same group as present in water, hence water and alcohol have similar properties.

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

(d) Both Assertion and Reason are false

9. Assertion- Saturated Hydrocarbons are chemically less reactive.

Reason- All the valencies of carbon atom are satisfied by single covalent bond.

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

(d) Both Assertion and Reason are false

10. Sonali’s mother has cracked hands due to washing clothes regularly. Explain the possible reasons of

it?

11. Substance 'X' is a moderate conductor of electricity. The structure of substance 'X' is as shown

below:

Which statements about substance 'X' are correct:

(I) It is covalent compound.

(II) It has a giant molecular structure.

(III) It has the same structure as graphite.

(IV) It has the same structure as diamond.

(a) (I) and (III). (b) (II) and (III). (c) (II) and (IV).

(d) (I), (II) and (IV)

12. Structures of two different forms of Carbon are given below:

Identify the two forms (I and II respectively) and how they related to each other?

(a) Diamond, Graphite, Isotopes of Carbon

(b) Graphite, Diamond, Allotropes of Carbon

(d) C14, C12, Isotopes of Carbon

13. Several factories were pouring their wastes in rivers A and B. Water samples were collected from

these two rivers. It was observed that sample collected from river A was acidic while that of river B

was basic. The factories located near A and B are

(a) Soaps and detergents factories near A and alcohol distillery near B.

(b) Soaps and detergents factories near B and alcohol distillery near A.

(d) Lead storage battery manufacturing factories near B and soaps and detergents factories near A.

14. The table shows the formulae of three organic compounds that belong to the same homologous

series.

What is the general formula of this series?

(a) CnH2nO. (b) CnH2n+2O. (c) CnH2nOH. (d) C2H2n+2OH

15. Which of the following compounds belong to same homologous series?

(a) S and T. (b) T and U. (c) P and U. (d) P and T

16. Write the name and structure of a saturated compound in which the carbon atoms are arranged in a

ring. Give the number of single bonds present in this compound.

17. Assertion: Vegetable oils are unsaturated, react with hydrogen in presence of nickel to form

vegetable ghee.

Reason: This reaction is saponification.

a) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).

(b) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).

(d) (A) is false, but (R) is true.

18. Assertion (A) : Esterification is a process in which a sweet smelling substance is produced.

Reason (R): When esters react with sodium hydroxide, an alcohol and sodium salt of carboxylic acid

are obtained.

(a) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).

(b) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).

(d) (A) is false, but (R) is true.

19. Assertion (A) : Ethanoic acid is also known as glacial acetic acid.

Reason (R) : The melting point of pure ethanoic acid is 290 K and hence it often freezes during

winters in cold climates.

(a) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).

(b) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).

(d) (A) is false, but (R) is true.

20. A student studies that acetic acid is a saturated compound. The structure of the compound is

shown.

Why is acetic acid classified as a saturated

compound?

a) because there is a the single bond between the

carbon atoms

b) because there is a double bond between the carbon

and oxygen atoms

c) because there is a single bond between the carbon

and hydrogen atoms

d) because there is a single bond between the carbon

and hydroxide diatom

21. Which of these carbon compounds represents an alkene?

22. The image represents a carbon compound

Which functional group is present in the compound?

(a) alcohol

(b) aldehyde

(d) ketone

23. Which of these series can be classified as homologous series?

(a) CHCl3, C2H5OH, C3H7OH

(b) CH3OH, C2H5OH, C3H7OH

(d) CH3COOH, C4H9OH, C2H5OH

24. A carbon compound contains two atoms of carbon. Which name should the carbon compound

bear?

(a) Butane

(b) Ethane

(d) Propane

25. The image represents the structure of a carbon compound known as ethane.

Which option explains the naming of ethane?

(a) the presence of functional group connected with a single bond

(b) as it contains two carbon atoms and a single bond connects the carbon atoms

(d) as it contains six hydrogen atoms and a single bond connects the carbon and

hydrogen atom.

26. The chemical reaction shows the addition of chlorine gas to hydrocarbon in the presence of

sunlight.

How does chlorine react to a

hydrocarbon compound in the presence of sunlight?

(a) it adds hydrogen into the compound

(b) it adds an oxygen atom into the compound

(d) it breaks double and triple bonds into a single bond

27. A student conducts an activity where he took ethanoic acid and ethanol in the presence of an

acid catalyst. He noticed that the resulted product has some sweet-smelling fragrance. What is

likely to be the product?

(a) CH3COOC2H5 + H2O

(b) CH3COOH + H2O

(d) COOH + H2O

28. A student studies that a soap molecule has two ends, one of which is an ionic end and the

other is the carbonic chain. Which option explains the interaction of a soap molecule with oil?

(a) ionic end of the soap interacts with the oil

(b) the closest end of the soap interacts with the oil

(d) ends of the soap randomly interact with the oil

29. The image represents a chemical reaction where an unsaturated hydrocarbon is converted

into a saturated hydrocarbon in the presence of a catalyst.

Which option

identifies the

action of the

catalyst?

(a) it causes a

reaction to

proceed

without the

reaction itself

being affected

(b) it causes the removal of all hydrogen atom bonded to the carbon atom

(d) causes the production of oxygen during the reaction

30.

Name this compound.

31. On the basis of bonding of carbon atoms identify the physical form in which carbon exists.

32. Write the chemical equation to show what happen when methane is treated with chlorine in the

presence of sunlight ?

33.

Identify the one compound out of two which has the functional group ketone.

34. Write any one difference between saturated & unsaturated carbon compounds

35.

Name the dehydrating agent in the given reaction.

36. Assertion (A) : Carbon monoxide is extremely poisonous in nature.

Reason (R) : Carbon monoxide is formed by complete combustion of carbon.

a) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).

(b) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).

(d) (A) is false, but (R) is true.

37. Assertion(A) : Carbon is the only element that can form large number of compounds.

Reason (R) : Carbon is tetravalent and shows the property of catenation.

(a) Both (A) and (R) are true and (R) is the correct explanation of the assertion (A).

(b) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).

(d) (A) is false, but (R) is true.

38. Assertion(A) : If the first member of a homologous series is methanal, its third member will be

propanal.

Reason (R) : All the members of a homologous series show similar chemical properties. (a) Both (A)

and (R) are true and (R) is the correct explanation of the assertion (A).

(b) Both (A) and (R) are true, but (R) is not the correct explanation of the assertion (A).

(d) (A) is false, but (R) is true.

39. Write the name and formula of the 2nd member of the homologous series having the

general formula CnH2n.

40. How many covalent bonds are there in a molecule of ethane, C2H6?

41. Where in the nature you can find the products of esterification reaction? Give one

example

42. Which of the following statements are correct for carbon compounds?

(i) Most carbon compounds are good conductors of electricity.

(ii) Most carbon compounds are poor conductors of electricity.

(iii) Force of attraction between molecules of carbon compounds is not very strong.

(iv) Force of attraction between molecules of carbon compounds is very strong.

(a) (ii) and (iv)

(b) (ii) and (iii)

(d) (i) and (iii

43. The number of isomers of pentane is

(a) 2

(b) 3

(d)

44. Identify ‘A’ in the following reaction:

CH3COOH + Na2CO3 → A + CO2 + H0O

(a) CH3COONa

(b) CH2(Na)COOH

(d) NaHCO

45. Which of the following belongs to homologous series of alkynes?

C6H6, C2H6, C2H4, C3H4.

(a) C6H6

(b) C2H4

(d) C3H

46. A hydrocarbon has four carbon atoms. Give its molecular formula if it is an alkene.

(a) C4H10

(b) C4H8

(d) C4H

47. A soap molecule has a

(a) hydrophobic head and hydrophobic tail

(b) hydrophobic head and hydrophilic tail

(d) hydrophilic head and hydrophobic tai

48. How would you distinguish experimentally between an alcohol and a carboxylic

acid?

49.

50.

VSA 2 MARKS EACH

1. Suggest reason for the element carbon forms a very large number of compounds.

2. Vinegar is used to give sour taste to food. Is there any other natural product that can be used in its

place? Suggest any two.

3. Calculate the molecular mass of ethanol, if molecular mass of ethane is 30 u?

4. Select saturated hydrocarbons from the following: C3H6; C5H10; C4 H10; C6H14; C2H4.

5. Define the term functional group. Identify the functional group present in CH3OH

6. Carbon, a member of group 14, forms a large number of carbon compounds estimated to be about

three million. Why is this property not exhibited by other elements of this group? Explain.

7. List two characteristics of covalent compounds.

8. Why are detergents preferred over soaps for washing cloths in hard water? Explain.

9. Carbon does not form iconic compounds. Why?

10. Why no leather formation take place when soap is added to hard water?

11. Draw the structure of cyclopentane ,also write the number ofcovalentbonds in it.

12. Give reason for the following :

a)Acetylene burns with a sooty flame

b)Kerosene does not decolourise bromine water while cooking oils do.

13. Butter does not decolorize bromine water, whereas cooking oil does. Comment.

14. Two carbon compounds ‘X’ and ‘Y’ have the molecular formula C3H6 and

C4H10 respectively. Which one of the two is most likely to show addition reaction?

Justify your answer. Also, give a chemical equation to explain the process of addition

in this case.

15. Explain the mechanism of the cleaning action of soaps.

SA 3 MARKS EACH

1. An organic compound ‘A’ of molecular formula C2H6O on oxidation with dilute alkaline KMnO4

solution gives an acid ‘B’ with the same number of carbon atoms. Compound A is often used for

sterilization of skin by doctors. Identify Compound A and B. Mention the chemical equation

involved in the formation of B from A.

2. A test tube contains a brown liquid in it. The colour of the liquid remains the same when methane is

passed over it but it disappears when ethane is passed over it. Suggest the name of the liquid brown

in colour.

Give reason for this phenomenon.

3. You are given ball and stick model of six carbon atoms and fourteen hydrogen atomsand sufficient

number of sticks. In how many ways one can join the models of six carbon atoms and fourteen

hydrogen atomsto form different molecules of C6H14.

4. (I) Draw the electron-dot structure for ethyne. (II) A mixture of ethyne and oxygen is burnt for

welding. In your opinion, why cannot we use a mixture of ethyne and air for this purpose?

5. On dropping a small piece of sodium in a test tube containing carbon compound ‘X’ with molecular

formula C2H6O, a brisk effervescence is observed and a gas ‘Y’ is produced. On bringing a burning

splinter at the mouth of the test tube the gas evolved bums with a pop sound.

(I) Identify ‘X’ and ‘Y’.

(II) Also write the chemical equation for the reaction.

(III) Write the name and structure of the product formed, when you heat ‘X’ with excess cone,

sulphuric acid.

6. 3 ml of ethanol is taken in a test tube and warmed gently in a water bath. A 5% solution of alkaline

potassium permanganate is added first drop by drop to this solution, then in excess.

(i) How is 5% solution of KMnO4 prepared?

(ii) State the role of alkaline potassium permanganate in this reaction. What happens on adding it in

excess?

(iii) Write chemical equation of this reaction.

7. What is hydrogenation? Write its industrial applications?

8. Give a test that can be used to differentiate between a butter and cooking oil.

9. Why is high temperature not favourable for alcoholic fermentation?

10. Draw the electron dot structure of carbon dioxide.

How can we confirm that the gas produced in any reaction is carbon dioxide.

Also write the reaction involved .

11. a)State the reason why carbon can neither form C4+ cations nor C4-

anions, but forms covalent bonds.

b)Also state reasons to explain why covalent compounds are bad conductors of electricity

12. A compound X is formed by the reaction of carboxylic acid C2H4O2 and alcohol in the presence of a

few drops of H2SO4. The alcohol on oxidation with alkaline KMnO4 followed by acidification gives

the same carboxylic acid as used in this reaction.

Give the names of (a) carboxylic acid, (b) alcohol.

Also, write the reaction.

13. Give the electron dot structure of chloro-methane. Also, write the formula and the name of

the next homologue of it.

14. What are the two properties of carbon that lead to the huge number of carbon

compounds we see around us? Explain

15. A gas is evolved when ethanol reacts with sodium. Name the gas evolved and also write

the balanced chemical equation of the reaction involved.

CASE BASED QUESTIONS 4 MARKS

1. (a) Carbon form compounds mainly by covalent bonding. Explain.

(b) An organic acid ‘X’ is a liquid which often freezes during winter time in cold countries,

has the molecular formula, C2H4O2. On warming it with methanol in the presence of a few

drops of concentrated sulphuric acid, a compound ‘Y’ with a sweet smell is formed.

(i) Identify ‘X’ and ‘Y’.

(ii) Give chemical equation for the reaction involved.

Cbselearn

Wednesday, February 28, 2024

Std 10 Chapter 1,2,3,4 important questions

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