CBSE Class 10 Science 2020 — Set 1

Questions in this 2020 Science paper (Set 1)

All 30 questions from this set, exactly as asked. Try each one, then open the question-paper PDF above for the complete paper.

1. 1.
   Name a cyclic unsaturated carbon compound.
2. 2.
   The change in magnetic field lines in a coil is the cause of induced electric current in it. Name the underlying phenomenon.
3. 3 (a).
   The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. Reproduction is the process by which organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body growth is still going on. Some degree of sexual maturation does not…
4. 3 (b).
   The growing size of the human population is a cause of concern for all people. Various contraceptive devices are being used by human beings to control the size of population. (b) What is the result of reckless female foeticide?
5. 3 (c).
   The growing size of the human population is a cause of concern for all people. Various contraceptive devices are being used by human beings to control the size of population. (c) Which contraceptive method changes the hormonal balance of the body?
6. 3 (d).
   The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. (d) Write two factors that determine the size of a population.
7. 4 (a).
   Human body is made up of five important components, of which water is the main component. Food as well as potable water are essential for every human being. The food is obtained from plants through agriculture. Pesticides are being used extensively for a high yield in the fields. These pesticides are absorbed by the plants from the soil along with water and minerals and from the water bodies…
8. 4 (b).
   Pesticides are absorbed by the plants from the soil along with water and minerals. As these chemicals are not biodegradable, they get accumulated progressively at each trophic level. (b) Give one method which could be applied to reduce our intake of pesticides through food to some extent.
9. 4 (c).
   Various steps in a food chain represent:

   • (a) Food web
   • (b) Trophic level
   • (c) Ecosystem
   • (d) Biomagnification
10. 4 (d).
    With regard to various food chains operating in an ecosystem, man is a:

    • (a) Consumer
    • (b) Producer
    • (c) Producer and consumer
    • (d) Producer and decomposer
11. 5.
    Calcium oxide reacts vigorously with water to produce slaked lime. CaO(s) + H₂O(l) → Ca(OH)₂(aq) This reaction can be classified as: (A) Combination reaction (B) Exothermic reaction (C) Endothermic reaction (D) Oxidation reaction Which of the following is a correct option?

    • (a) (A) and (C)
    • (b) (C) and (D)
    • (c) (A), (C) and (D)
    • (d) (A) and (B)
12. 6.
    In a double displacement reaction such as the reaction between sodium sulphate solution and barium chloride solution: (A) exchange of atoms takes place (B) exchange of ions takes place (C) a precipitate is produced (D) an insoluble salt is produced The correct option is:

    • (a) (B) and (D)
    • (b) (A) and (C)
    • (c) only (B)
    • (d) (B), (C) and (D)
13. 7.
    Baking soda is a mixture of:

    • (a) Sodium carbonate and acetic acid
    • (b) Sodium carbonate and tartaric acid
    • (c) Sodium hydrogen carbonate and tartaric acid
    • (d) Sodium hydrogen carbonate and acetic acid
14. 8.
    The chemical formula for plaster of Paris is:

    • (a) CaSO₄·2H₂O
    • (b) CaSO₄·H₂O
    • (c) CaSO₄·½H₂O
    • (d) 2CaSO₄·H₂O
15. 9.
    The laws of reflection hold true for:

    • (a) plane mirrors only
    • (b) concave mirrors only
    • (c) convex mirrors only
    • (d) all reflecting surfaces
16. 10.
    At the time of short circuit, the electric current in the circuit:

    • (a) varies continuously
    • (b) does not change
    • (c) reduces substantially
    • (d) increases heavily
17. 11.
    Which one of the following is responsible for the sustenance of underground water?

    • (a) Loss of vegetation cover
    • (b) Diversion for high water demanding crops
    • (c) Pollution from urban wastes
    • (d) Afforestation
18. 12.
    Incomplete combustion of coal and petroleum: (A) increases air pollution (B) increases efficiency of machines (C) reduces global warming (D) produces poisonous gases The correct option is:

    • (a) (A) and (B)
    • (b) (A) and (D)
    • (c) (B) and (C)
    • (d) (C) and (D)
19. 13.
    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. Select the correct option:

    • (a) Both A and R are true and R is correct explanation of the Assertion.
    • (b) Both A and R are true but R is not the correct explanation of the Assertion.
    • (c) A is true…
20. 14.
    Assertion (A): In the process of nuclear fission, the amount of nuclear energy generated by the fission of an atom of uranium is so tremendous that it produces 10 million times the energy produced by the combustion of an atom of carbon from coal. Reason (R): The nucleus of a heavy atom such as uranium, when bombarded with low energy neutrons, splits apart into lighter nuclei. The mass difference…
21. 15.
    1 g of copper powder was taken in a china dish and heated. What change takes place on heating? When hydrogen gas is passed over this heated substance, a visible change is seen in it. Give the chemical equations of reactions, the name and the colour of the products formed in each case.
22. 16.
    List the important products of the Chlor-alkali process. Write one important use of each.
23. 17.
    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 the chemical equation of this reaction.
24. 18.
    A squirrel is in a scary situation. Its body has to prepare for either fighting or running away. State the immediate changes that take place in its body so that the squirrel is able to either fight or run.
25. 19.
    Define the term pollination. Differentiate between self pollination and cross pollination. What is the significance of pollination?
26. 20.
    What are homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor? Justify your answer.
27. 21.
    Why is Tyndall effect shown by colloidal particles? State four instances of observing the Tyndall effect.
28. 22.
    Draw a labelled diagram to show

    • (i) reddish appearance of the sun at the sunrise or the sunset and
    • (ii) white appearance of the sun at noon when it is overhead.
29. 23.
    A V-I graph for a nichrome wire is given below. What do you infer from this graph? Draw a labelled circuit diagram to obtain such a graph.
30. 24 (a).
    Write the mathematical expression for Joule's law of heating.
31. 24 (b).
    Compute the heat generated while transferring 96000 coulomb of charge in two hours through a potential difference of 40 V.
32. 25.
    Carbon cannot reduce the oxides of sodium, magnesium and aluminium to their respective metals. Why? Where are these metals placed in the reactivity series? How are these metals obtained from their ores? Take an example to explain the process of extraction along with chemical equations.
33. 26.
    The position of certain elements in the Modern Periodic Table are shown below. Group: 1 2 3 to 12 13 14 15 16 17 18 Period 1: G H Period 2: A I B C Period 3: D E F Using the above table answer the following questions giving reasons in each case:

    • (i) Which element will form only covalent compounds?
    • (ii) Which element is a non-metal with valency 2?
    • (iii) Which element is a metal with valency 2?…
34. 27 (a).
    Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms? Explain. (b) Draw a diagram of human respiratory system and label — pharynx, trachea, lungs, diaphragm and alveolar sac on it.
35. 28.
    What is the law of dominance of traits? Explain with an example. (b) Why are the traits acquired during the life time of an individual not inherited? Explain.
36. 29.
    Draw a ray diagram in each of the following cases to show the formation of image, when the object is placed:

    • (i) between optical centre and principal focus of a convex lens.
    • (ii) anywhere in front of a concave lens.
    • (iii) at 2F of a convex lens. State the signs and values of magnifications in the above mentioned cases
    • (i) and (ii).
37. 30.
    What is an electromagnet? List any two uses. (b) Draw a labelled diagram to show how an electromagnet is made. (c) State the purpose of soft iron core used in making an electromagnet. (d) List two ways of increasing the strength of an electromagnet if the material of the electromagnet is fixed.

Class 10 Science exam pattern (80 marks)

The theory paper carries 80 marks over 3 hours (39 questions, with internal choice in some). Section-wise structure:

Structure per the CBSE 2023-24 sample-paper design; question wording varies by set.

Prepare with

How to use these papers

1. 1Start chapter-wise early in the year — solve only the Science questions from a chapter you have just finished.
2. 2Switch to full timed papers 2–3 months before the exam: one complete set in the real time limit, no notes.
3. 3Self-mark against the marking scheme, then fix every mistake with our free NCERT solutions.
4. 4Re-attempt your weakest chapters until the recurring question types feel routine.

CBSE Class 10 Science 2020 paper — FAQ