SCIENCE MOST IMPORTANT QUESTIONS
CHAPTERWISE CLASS 10
Q1. Solid calcium
oxide was taken in a container and water was added slowly to it. (CBSE 2013,
2019)
1. (a) Write the
observations. (b) Write the chemical formula of the product formed.
2.What change in color is observed when white silver
chloride is left exposed to sunlight? State the type of chemical reaction in
this change. (CBSE 2014, 2019, 2023)
3.Write the chemical equation of the reaction in which the
following changes take place with an example of each. (CBSE 2023, 2015) (a)
Change in color (b) Change in temperature
4. In the
electrolysis of water, (CBSE 2020, 2013, SP-2018) A. Name of the gases
liberated at anode & cathode. B. Why is it that the volume of gas collected
on one electrode is two times that on the other electrode? C. What would happen
if dilute H S0 is not added to water?
5. A shining metal
‘M’ on burning gives a dazzling white flame & changes to a white powder
‘N’. (CBSE 2020, 2022) A. Identify ‘M’ & ‘N’. B. Represent the above
reaction in the form of a balanced chemical equation. C. Does ‘M’ undergo
oxidation or reduction in this reaction? Justify.
6.List the important products of the chlor-alkali process.
Write one important use of each. (CBSE 2020, 2023)
7. (a) Identify the acid and the base whose combination
forms the common salt that you use in your food. Write its chemical formula and
chemical name of the salt. (b) What is rock salt? (c) Mention its color and the
reason due to which it has this colour. (CBSE 2019, 2013)
8.Write the chemical equations when zinc granules react
with: (a) Sulphuric acid (b) Hydrochloric acid (CBSE 2014, 2020)
9. How is sodium
hydroxide produced? Write the balanced chemical equation also. Why is this
process called the chlor-alkali process? In this process name the products
given off at: (a) anode (b) cathode. (CBSE 2022, 2015)
10. Give the reasons for the following: (i) Only one half of
water molecule is shown in the formula of plaster of Paris. (CBSE 2020, CBSE SP
- 2017)
11. Why do ionic compounds conduct electricity in molten
state and not in solid state? (CBSE 2014, 2023)
12. The reaction of metal X with Fe O is highly exothermic
and is used to join railway tracks. Identify metal X. Write the chemical
equation for the reaction. (CBSE 2016, 2023)
13. Zinc is a metal found in the middle of the activity
series of metals. In nature, it is found as a carbonate ore, ZnCO . Mention the
steps carried out for extraction from the ore. (CBSE 2023, 2013)
14. Differentiate between roasting and calcination giving
chemical equations for each. (CBSE 2013, 2023)
15. Why are copper vessels corroded with a green coating in
the rainy season? (CBSE 2015, 2016, 2019)
16.Draw the electron dot structure of Nitrogen. (CBSE 2023,
2021)
17.Write the chemical formula of benzene and draw its structure.
(CBSE 2017, 2021, 2023)
18. What will you observe on adding a 5% alkaline KMnO
solution drop by drop to some warm ethanol taken in a test tube? Write the name
of the compound formed during the above chemical reaction. (CBSE 2013, 2020)
19.Why do covalent compounds have low melting and boiling
points? (CBSE 2020, 2021) 5.What is meant by a homologous series of carbon
compounds? Write the general formula of (CBSE 2015, 2014, 2016,2019) (a)
alkenes (b) alkynes
20.(a) What is double circulation? (b) Why is the separation
of the right side and the left side of the heartful useful ? How does it help
birds and mammals? (CBSE 2023, 2022, 2019)
21.Explain the ways
in which glucose is broken down in the absence or storage of oxygen? (CBSE
2017, 2018, 2019)
22. (a) Write two water-conducting tissues present in
plants. How does water enter continuously into the root xylem? (b) Explain why
plants have low energy needs as compared to animals. (CBSE 2017, 2019, 2021)
23. In single-celled organisms, diffusion is sufficient to
meet all their requirements for food, gas exchange, or removal of waste, but it
is not in the case of multicellular organisms. Explain the reason for the
difference. (CBSE 2015, 2019, 2022)
24. Draw a diagram of
the human alimentary canal and label the following: (CBSE 2016, 2019, 2020)
(1) part in which starch digestion is initiated (2) organ in
which bile is stored (3) the gland that secretes digestive enzymes as well as
hormones. (4) Part of the alimentary canal where water is reabsorbed. (5) Parts
of the gut where finger-like projections are present to facilitate absorption
of digested food.
25. Name a plant
hormone responsible for bending of a shoot of a plant when it is exposed to
unidirectional light. How does it promote phototropism ? (CBSE 2019, 2023)
26. With the help of suitable examples explain the terms
phototropism, geotropism and chemotropism, (CBSE 2016, 2020)
27. Draw a diagram of the cross-sectional view of the human
brain label the parts of the brain with the functions. (CBSE 2017, 2020)
28.. How does the feedback mechanism regulate hormone
secretion? Explain with the help of an example ? (CBSE 2017, 2019)
29. Name the part of
human brain which control the voluntary and involuntary actions. (CBSE 2017,
2018)
30. Difference between the asexual and sexual reproduction ?
Also, give one example of each. (CBSE 2016, 2018, 2021, 2022)
31. Describe reproduction by spores in Rhizopus. (CBSE 2017,
2015, 2020, 2022)
32. List three techniques that have been developed to
prevent pregnancy. Which one of these techniques is not meant for males ? How
does the use of these techniques have a direct impact on the health and
prosperity of a family ? (CBSE 2017, 2018, 2020)
33. a. Draw a diagram of human female reproductive system
and label the parts: Which produce an egg, Where fertilization takes place B.
List two bacterial diseases which are transmitted sexually. C. What are
contraceptive devices? Give two reasons for adopting contraceptive devices in
humans. (CBSE 2019, 2017, 2016)
34. Define pollination. Explain the different types of
pollination. List two agents of pollination. How does suitable pollination lead
to fertilization ? (CBSE 2019, 2016, 2021) How do organisms reproduce? .Mention
any two points of difference between acquired and inherited traits. If the tail
of a mouse is cut for twenty one generations, will the tail occur in the twenty
second generation of that mouse? Give reason to support your answer. (CBSE
2013, 2016, 2017, 2022, 2021)
35. Two pea plants- one with round yellow seeds (RRYY) and
another with wrinkled green (rryy) seeds produce F1 progeny that have round,
yellow (RrYy) seeds. When F1 plants are self-pollinated, which new combination
of characters is expected in F2 progeny? How many seeds with these new
combinations of characters will be produced when a total 160 seeds are produced
in F2 generation? Explain with reason. (CBSE 2018, 2020, 2022)
36.List difference between dominant traits and recessive
traits. What percentage of the plants in the F2 generation were round, in
Mendel’s dihybrid cross between round yellow and wrinkled green pea plants ?
(CBSE 2016, 2015, 2019)
37.Sahil performed an
experiment to study the inheritance pattern of genes. He crossed tall pea
plants (TT) with short pea plants (tt) and obtained all tall plants in F1
generation. a. What will be the set of genes present in the F1 generation? b.
Give reason why only tall plants are observed in F1 progeny. (CBSE 2016, 2021,
2022)
38..In an asexually reproducing species, if a trait X exists
in 5% of a population and trait Y exists in 70% of the same population, which
of the two traits is likely to have arisen earlier? Give reason. (CBSE 2019,
2021)
39.State the two laws of reflection of light. (CBSE 2011,
2013 2014)
40.The absolute
refractive indices of glass and water are 1.5 and 1.33 respectively. In which
medium does light travel faster? Calculate the ratio of speeds of light in the
two media. (CBSE 2013, 2019, 2020) 41.The image of a candle flame placed at a
distance of 30 cm from a mirror is formed on a screen placed in front of the
mirror at a distance of 60 cm from it pole. What is the nature of the mirror?
Find its focal length. If the height of the flame is 2.4 cm, find the height of
its image. State whether the image formed is erect or inverted. (CBSE 2014, 2015,
2017)
42.Draw ray diagram
to show the path of the refracted ray in each of the following cases. A ray of
light incident on a concave lens (i) is parallel to its principal axis, (ii) is
passing through its optical centre and (iii) is directed towards its principal
focus. (Delhi 2013, CBSE 2015, 2016)
43..An object is placed at a distance of 50 cm from a
concave lens of focal length 30 cm. (i) Use lens formula to find the distance
of the image from the lens. (ii) List four characteristics of the image(nature,
position, size, erect/inverted) formed by the lens in this case. (iii) Draw a
ray diagram to justify your answer of pair (ii). (CBSE 2016, 2019)
44. What is ‘dispersion of white light’? State its cause.
Draw a ray diagram to show the dispersion of white light by a glass prism.
(CBSE 2011, 2013, 2016, 2017)
45. How will you use two identical glass prisms so that a
narrow beam of white light incident on one prism emerges out of the second
prism as white light? Draw and label the ray diagram. (CBSE 2016, 2017, 2019,
2020)
46.Draw a ray diagram
to show the refraction of light through a glass prism. Mark on it (a) the
incident ray, (b) the emergent ray and (c) the angle of deviation. (CBSE 2011,
2013, 2017)
47. State the function of each of the following parts of
human eye: (i) Cornea (ii) Iris iii) Pupil (CBSE 2013, 2016, 2018)
48.A student is unable to see clearly the words written on
the black board placed at a distance of approximately 3 m from him. Name the
defect of vision the boy is suffering from. State the possible causes of this
defect and explain the method of correcting it. (CBSE 2017, 2018)
49. (a) Prove that the equivalent resistance of three
resistors R1, R2 and R3 in series is R1 + R2 + R3. (b) You have four resistors
of 8 each. Show how would you connect these resistors to have effective
resistance of 8Ω ? (2013, 2015, 2016)
50. State Ohm's law. Draw a labelled circuit diagram to
verify this law in the laboratory. If you draw a graph between the potential
difference and current flowing through a metallic conductor, what kind of curve
will you get? Explain how would you use this graph to determine the resistance
of the conductor. (2014, 2015, 2016)
51.(i)State one
difference between kilowatt and kilowatt hour. Express 1 kWh in joules. (ii) A
bulb is rated 5V; 500 mA. Calculate the rated power and resistance of the bulb
when it glows. (2013, 2016)
52. Two lamps, one rated 100 W; 220 V, and the other 60 W;
220 V, are connected in parallel to electric mains supply. Find the current
drawn by two bulbs from the line, if the supply voltage is 220 V. (2018. 2014)
53.Draw a schematic diagram of a circuit consisting of a
battery of 3 cells of 2 V each, a combination of three resistors of 10Ω, 20Ω
and 30Ω connected in parallel, a plug key and an ammeter, all connected in
series. Use this circuit to find the value of the following: (a) Current
through each resistor (b) Total current in the circuit (c) Total effective
resistance of the circuit. (2020)
51. State whether an alpha particle will experience any
force in a magnetic field if (alpha particles are positively charged particles)
(i) it is placed in the field at rest. (ii) it moves in the magnetic field
parallel to field lines. (iii) it moves in the magnetic field perpendicular to
field lines. Justify your your answer in each case. (CBSE 2016, 2022, 2023)
52. Mention and explain the function of an earth wire. Why
it is necessary to earth metallic appliances? (CBSE 2014, 2016, 2020)
53. Name and state the rule which is used to determine the
direction of force on a current carrying conductor placed in a magnetic field.
(CBSE 2020, 2022, 2023)
54. What are magnetic field lines? Justify the following
statements: (a) Two magnetic field lines never intersect each other. (b)
Magnetic field are closed curves. (CBSE 2013, 2015, 2016)
55. What is solenoid? Draw the pattern of magnetic field
lines of (i) a current carrying solenoid and (ii) a bar magnet. List two
distinguishing features between the two fields. (Delhi 2019, 2020)
56. How is ozone formed in the higher levels of the
atmosphere? “ Damage to the ozone layer is a cause of concern”. Justify this
statement. (CBSE 2015, 2017, 2020, 2023)
57. We do not clean ponds or lakes, but an aquarium needs to
be cleaned regularly. Explain. (CBSE 2023, 2017)
58. Why are green
plants called the producers ? (CBSE 2019, 2015)
59. (a) How can we help in reducing the problem of waste
disposal? Suggest any three methods. (b) Distinguish between biodegradable and
non-biodegradable wastes. (CBSE 2013, 2015, 2019)
60. Define an ecosystem. Draw a block diagram to show the
flow of energy on an ecosystem. (CBSE 2015, 2017, 2019)
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