Important Questions - Metals Non metals

 

Ans: C

Q2.A non-metal X is an important constituent of our food. It forms two oxides Y and Z. Y is toxic and causes suffocation and even death while Z is responsible for global warming. Identify X, Y and Z.

(a)   X=C,Y=CO,Z=CO2

      (b)X=S,Y=SO2,Z=SO3

        ( c) X=p,Y=P2O3,Z=P2O5

       (d) X=O,Y=O2,Z=O3

Ans: A

 

 

 

 

Q3. A student adds an equal amount of copper sulphate solution in two beakers. He adds zinc in beaker P and silver in beaker Q. The student observes that the color of the solution in beaker P changes while no change is observed in beaker Q. Which option arranges the metals in increasing order of reactivity? *

(a) silver-zinc-copper    (b)zinc-copper- silver

 (c )silver-copper-zinc          (d)copper-silver-zinc

Ans: C

 

4. Which of the following is the correct arrange-ment of the given metals in ascending order of their reactivity?

Zinc, Iron, Magnesium, Sodium

(a) Zinc > Iron > Magnesium > Sodium

(b) Sodium > Magnesium > Iron > Zinc

(c) Sodium > Zinc > Magnesium > Iron

(d) Sodium > Magnesium > Zinc > Iron

Ans: D

 

 

 

 

 

 

 5. In thermite welding a mixture of …… and …… is ignited with a burning magnesium ribbon which produces molten iron metal as large amount of heat is evolved.

(a) iron (III) oxide and aluminium powder

(b) iron (II) oxide and aluminium powder

(c) iron (III) chloride and aluminium powder

(d) iron (III) sulphate and aluminium powder

Ans: A

 

 6. An alloy reacted with dilute hydrochloric acid to produce a gas which ‘pops’ a lighted splint. The residue reacted with dilute nitric acid to form a blue solution. Which one of the following pairs of metals is present in the alloy?

(a) Copper and lead

(b) Lead and magnesium

(c) Lead and zinc

(d) Copper and magnesium

Ans: d

7.  Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?

(i) Au

(ii) Cu

(iii) Na

(iv) K

(a) (i) and (ii)

(b) (i) and (iii)

(c) (ii) and (iii)

(d) (iii)and (iv)

Ans: a

 

 

 

Q8.Which one of the following four metals would be displaced from the solution of its salts by the other three metals?

(a) Mg

(b) Zn

(c) Ag

(d) Cu

Ans: C

Q9. A scientist is attempting to represent an ionic bond between calcium and chlorine. The figure below shows the progress he has made so far. What should be the next step in his representation of the ionic bond?

(a) Transfer an electron from the calcium atom to the chlorine atom.

(b). Transfer an electron from the chlorine atom to the calcium atom.

(c ) Add another chlorine atom to accept an electron from the calcium atom.

(d). Add another calcium atom to donate an electron to the chlorin​e

Ans: A

 

Q10.A student performs some activities on two substances and records the observations in a table as shown below:

 

Which option classifies the substance into metals and Non -Metals?

(a)Both substance are non metals

(b) both the substances are metals.

(c) substance M is a metal while N  is non metal substance

(d) M is a non metal while N is a metal

Ans: (c) substance M is a metal while N  is non metal substance

 

 

 

 

Q11. Which of the following two combinations are correct?

 

 

A. i and iii  B. i and iv  C. ii and iii  D. ii and iv

 

Ans: d

 

 

 

 

 

 

 

 

Q12. Which one of the following structure correctly depicts the compound cacl2​

 

Ans:D

 

 

 

Q13. Choose the incorrect match.

 (a) A metal used in joining electric wires - Magnesium

 (b) A metal whose oxide is soluble in both acids and bases - Zinc

(c) A metal unreactive towards oxygen and dilute acids - Gold

 (d) A metal extracted by using electrolytic reduction - Aluminium

Ans:A

 

Q14. What happens when calcium is treated with water?

(i) It does not react with water.

(ii) It reacts violently with water.

(iii) It reacts less violently with water.

(iv) Bubbles of hydrogen gas formed stick to the surface of calcium.

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

Ans: D

 

Q1. State the property utilised in the following:

(i) Graphite in making electrodes.

(ii) Electrical wires are coated with Polyvinyl Chloride (PVC) or a rubber-like material.

(iii) Metal alloys are used for making bells and strings of musical instruments.

 

Ans: i) Graphite is a non-metallic conductor of electricity 1 so is cheap, insoluble in water, acids and bases; and is non-corrosive material. Due to these properties, it is used in making electrodes.

(ii) Polyvinyl Chloride (PVC) or a rubber-like material are insulators and hence do not allow electrons to flow. Hence, these are used in coating the electrical wires.

(iii) Metals and metal alloys are generally sonorous in nature, i.e. they produce sound. Due to this property, they are used for making bells and strings of musical instruments.

 

 

Q2.     Choose the following metals to answer the questions below

(Aluminum, Copper, Calcium, Iron, Magnesium, Potassium, Nickel, Zinc)

Name a metal which

1. is manufactured by electrolysis of its molten oxide
2. is used to galvanaize Iron
3. is alloyed with Zinc to make Brass
4. reacts with aqueous copper(II)sulfate to give a pink solid
5. does not reacts with cold water

Ans: Metal manufactured by electrolysis of molten oxide is Aluminum

Metal used to galvanize the iron is Zinc

Metal alloyed with Zinc to make Brass is Copper

Metal reacts with aqueous copper(II)sulfate to give pink solid is Iron

 

Q3. A,B       and    C       are     3        elements     which          undergo      chemical          reactions    according   to      following equations:

 Answer      of      the     following:

i.        Which        element       is       most  reactive?

ii.       Which        element       is       least  reactive?

 Ans:

1)Reactivity series,B most reactiveA,C least reactive

2)B is the most reactive element

3) C is the least reactive element.

Q4. An element X on reacting with O2 form X2O. This Oxide dissolves in water and turns blue litmus paper red. Predict the nature of element whether it is a metal or a nonmetal.

Ans. The oxide is acidic in nature as it has turned blue litmus to red. Hence X is a nonmetal.

Q5. A metal ‘X’ is found in the form of filings which burns vigorously when sprinkle of flame. When these filings are treated with Sulphur a black colored compound ‘Y’ is formed which is not attracted by magnet. ‘X’ reacts with dil HCl to liberate hydrogen gas ‘X’ reacts with steam to from ‘Z’ along with hydrogen gas. Identify ‘X’, ‘Y’, and ‘Z’. Write the reaction  involved.

Elements 'X' is iron. Iron fillings burn vigorously when sprinkled on the flame. These react with sulphur to form ferrous sulphide which is a black colored compound.

Fe+S→FeS

Iron reacts with dil HCl to form ferrous chloride and hydrogen gas.

Fe+2HCl→FeCl2+H2

Iron reacts with steam to form Fe3O4and hydrogen gas 3Fe+4H2O→Fe3O4+4H2

So X is iron, Y is FeSand Z is Fe3O4

Q6. A chemical compound ‘X’ is used in the soap and glass industry. It is prepared from brine.

(a) Write the chemical name, common name and chemical formula of ‘X’.

(b) Write the equation involved in its preparation.(c) What happens when it is treated with water containing Ca and Mg salts?

Ans: (a) The chemical name is Sodium carbonate. Its common name is Washing Soda. The chemical formula of the compound in its hydrated form is Na2CO3 .10H2O   and the chemical formula in its anhydrous form is Na2CO3.

(b) Sodium carbonate is prepared in the industries by various processes. One such common process is the thermal decomposition of sodium bicarbonate. The reaction that is involved here is as follows:

 

Thus, in the manufacture process, we can find the use of brine (NaCl) in the production of sodium carbonate.

(c) As sodium carbonate is water-soluble and magnesium carbonate and calcium carbonate are insoluble, so it is used to soften water by removing Mg2+and Ca2+ Thus, when sodium carbonate is treated with water containing Ca and Mg salts, it removes them and thus, softens the water.

 

Q 7 Compounds containing oxygen are of great interest in the field of chemistry. Because of oxygen's high reactivity, it is most often found in compounds. Oxygen reacts rapidly with group 1 elements. All alkali metal oxides form basic solutions when dissolved in water. The principal combustion product is the most stable product with respect to the reactants. For example, with careful control of oxygen, the oxide M2O (where M represents any alkali metal) can be formed with any of the alkali metals. When a metal reacts with oxygen to form a metal oxide, a redox reaction occurs. Metal + Oxygen → Metal oxide Different metals burn in oxygen with different rates depending on their differing activeness. The more reactive metal towards oxygen, the brighter and faster the combustion of the metal. Given figure below shows the experiment is conducted to build the reactivity series of metals. Oxygen that is used in combustion of other metals is provided by heating solid potassium manganate (VII). When heated, lithium, sodium, potassium, rubidium, and cesium ignite through combustion reactions with oxygen. Glass wool Metal filing Heat up Heat up Potassium Manganate (VII) crystal

 

   Ans: (a) Metals such as silver and gold do not react with oxygen even at high temperatures as they are relatively inert. (b) Copper does not burn but is coated with black colored copper oxide. When heated, copper does not burn, but the hot copper metal is coated with a black coloured layer of copper (II) oxide. 2Cu + 02  2CuO (c) Almost all metals combine with oxygen to form metal oxides. Metal + Oxygen  Metal oxide Some metal oxides, such as sodium oxide and potassium oxide, dissolve in water to form alkalis: Moreover, some metal oxides, such as aluminium oxide and zinc oxide, show both acidic and basic nature and are known as amphoteric oxides. OR (c) The metal oxides sodium oxide and potassium oxide dissolve in water to form alkalis as follows: Na2O(s) + H20(l)  2NaOH(aq) K2O(s) + H20(l)  2 KOH(aq) 

 

Q8.A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH.

 

Aluminium and Iron are used in a thermite process, however, only aluminium when heated with oxygen, gives aluminium oxide, which is an amphoteric substance, meaning it can react with both acids and bases. Hence, A is aluminium and B is aluminium oxide.

 

The reaction of aluminium oxide with hydrochloric acid can be written as follows:

Al2O3+6HCl→2AlCl3+3H2O

The reaction of aluminium oxide with sodium hydroxide can be written as follows:

Al2O3+2NaOH→2NaAlO2+H2O

 

Q9.Give reasons: (i) Reactivity of Al decreases if it is dipped in HNO3. (ii) Carbon cannot reduce the oxides of Na or Mg. (iii) NaCl is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state. (iv) Iron articles are galvanised. (v) Metals like Na, K, Ca and Mg are never found in their free state in nature.

Ans: (a) Nitric acid is a strong oxidizing agent. Due to this, when aluminium is dipped in nitric acid, a layer of aluminium oxide is deposited on aluminium. As a result; reactivity of aluminium decreases when it is dipped in nitric acid.

(b) Sodium and magnesium are highly reactive metals. Hence, they have higher affinity to oxygen than to carbon. Due to this, carbon fails to reduce the oxides of sodium or magnesium.

(c)  NaCl is an ionic compound. Ionic compounds do not conduct electricity in solid state. But ionic compounds are good conductors of electricity in molten state and in aqueous solution.

(d) Iron has a tendency to react with atmospheric moisture. This process is called rusting and leads to corrosion of iron. Iron articles are galvanized to prevent rusting of iron.

(e) Na, K. Ca and Mg are highly reactive metals. They can easily form compound with most of the elements. Due to this, these metals are not found in their free state in nature.

 

 

Q10. (a) Write the chemical name of Na2CO3.10H2O and Na2CO3. (b) Write the significance of 10H2O. (c) Mention the term used for water molecules attached with a salt. (d) With the help of a chemical equation, explain the method of preparation of both Na2CO3.10H2O and Na2CO3. Also, list two uses of Na2CO3.10H2O.

 

Ans: Na2CO3.10H2O - Sodium carbonate decahydrate. Na2CO3 - Anhydrous sodium carbonate 10H2O - Water of crystallization which impacts shape and colour to the crystals. Preparation: NaCl + H2O + CO2 + NH3 → NH4CI +NaHCO3   2NaHCO3 +Heat→ Na2CO3 + H2O + CO2   Na2CO3 + 10H2O → Na2CO3.10H2O Uses: (i) Used in glass, soap and paper industries. (ii) Used in the manufacture of borax. (iii) Used as a cleansing agent for domestic Purpose.

 

Q11. Nikita took Zn, Al, Cu, Fe, Na and Mg metal. She then puts each metal win cold water and then in hot water. She reacted the metals with steam. 1) Name the metal(s) which reach with cold water 2)Name the metal(s) which react with steam 3)Name the metal(s) which react with hot water. 4)Arrange the metals in the decreasing order of their reactivity.

Ans. (i) Na (ii) Al, Zn, Fe (iii) Mg (iv) Na>Mg>Al>Zn>Fe>Cu

 

Q12. Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.

Answer the following questions based on above information:

(i) Which is the most active metal and why?

(ii) What would be observed if B is added to a solution of copper (II) sulphate and why?

(iii) Arrange the metals A, B, C and D in order of increasing reactivity.

(iv) Container of which metal can be used to store both zinc sulphate solution and silver nitrate solution. Give reason for your choice.

(v) Which of the above solutions can be easily stored in a container made up of any of these metals?

 

 

Ans:

(a) So, from the following results, we can conclude that B is the most reactive metal.

 

 

(b) When B is added to the copper sulphate solution then it will displace copper from copper sulphate.

 

 

(c) Increasing order of reactivity of A, B, C, and D is:

D < C < A < B.

 

 

(d) As D is less reactive from all the metal, so D can be used as a container to store zinc sulphate and silver nitrate solutions.

 

 

(e) Zinc sulphate can be easily stored in a container made up of these metals.