PYQ Vault

Day 123: CBSE Class 10 Science

5 questions (8 parts). Try each one first, then open its answer.

  1. Question 1

    Carbon and its Compounds. Asked once: 2025 (same type asked 3 times)

    4
    Given below are the structures of some hydrocarbons. Select the two structures which are related to each other from the given options :

    Tap an option to check your answer.

  2. Question 2

    Carbon and its Compounds. Asked once: 2023 (same type asked 3 times)

    36 (b)
    (i) What is saponification ? Differentiate between soaps and detergents on the basis of the following : (1) Their chemical composition (2) Their mechanism in hard water (ii) Explain the formation of micelles between oily dirt and soap molecules. Also draw its diagram.

  3. Question 3 (case study, 4 parts)

    Carbon and its Compounds. Asked once: 2024 (same type asked 3 times)

    Carbon is a versatile element that forms the basis of all living organisms and many of the things we use. A large variety of compounds is formed because of its tetravalency. Compounds of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine and many other elements.
    37 (a)
    What are hydrocarbons ?
    37 (b)
    List two properties by virtue of which carbon can form a large number of compounds.
    37 (c) (i)
    Write the formula of the functional group present in (1) aldehydes, and (2) ketones. Write chemical equation for the reaction that occurs between ethanoic acid and ethanol in the presence of a catalyst.
    37 (c) (ii)
    What are structural isomers ? Write the structures of two isomers of butane (C4H10)(\mathrm{C_4H_{10}}).

  4. Question 4

    Chemical Reactions and Equations. Asked once: 2025 (same type asked 3 times)

    27
    Explain why respiration is considered as an exothermic reaction. Give the chemical equation for this reaction.

  5. Question 5

    Chemical Reactions and Equations. Asked once: 2025 (same type asked 3 times)

    21
    A crystalline substance of green colour ‘X’ emits gases of characteristic odour when heated over a flame. It first loses water and changes colour. On further heating, it decomposes and produces a solid compound Y. (a) Identify ‘X’ and ‘Y’. (b) State the change in colour observed when ‘X’ is heated.