PYQ Vault

Day 68: CBSE Class 10 Science

5 questions. Try each one first, then open its answer.

  1. Question 1

    Acids, Bases and Salts. This type asked 2 times: 2024, 2025. This one: 2025

    7
    The water of crystallization is present in (i) Bleaching Powder (ii) Plaster of Paris (iii) Washing Soda (iv) Baking Soda

    Tap an option to check your answer.

  2. Question 2

    Carbon and its Compounds. This type asked 2 times: 2023, 2025. This one: 2025

    34 (B)
    A carbon compound ‘A’ is widely used as a preservative in pickles and has a molecular formula C2H4O2\mathrm{C_2H_4O_2}. This compound reacts with ethanol to form a sweet smelling compound ‘B’. (i) Identify the compound ‘A’ and write its structure. (ii) Write the chemical equation for the reaction of ‘A’ with ethanol to form compound ‘B’. State the role of presence of an acid in the reaction. (iii) How can we get compound ‘A’ back from ‘B’ ? (iv) How can ‘A’ be obtained from ethanol ? (v) Name the gas produced when compound ‘A’ reacts with washing soda.

  3. Question 3

    Carbon and its Compounds. This type asked 2 times: 2024, 2025. This one: 2025

    5
    Choose the incorrect statement about the common reaction used in hydrogenation of vegetable oils.

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  4. Question 4

    Carbon and its Compounds. This type asked 2 times: 2023, 2025. This one: 2025

    35 (b)
    (i) What is a homologous series of carbon compounds ? Write the name and formula of three successive members of the homologous series of compounds having functional group −COOH\mathrm{{-}COOH}. (ii) Write the name of two carbon compounds in which carbon atoms are arranged in the form of a ring. Draw the structure of any one of the two.

  5. Question 5

    Chemical Reactions and Equations. This type asked 2 times: 2024, 2025. This one: 2025

    27 (a)
    (i) Define the term decomposition reaction. Write one chemical equation each for decomposition reaction where energy is supplied in the form of heat, light or electricity. (ii) Decomposition of vegetable matter into compost is considered an exothermic reaction. Why ?