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Carbon is a versatile element… (Class 10 Science 2024, Q37)

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ScienceCBSE Class 10 · Board exam 2024, set 31/5/1 · 4 marks · Case-based

CBSE Class 10 Science 2024: question 37

Set in the CBSE Class 10 board exam of 2024, paper 31/5/1, section E, question 37, for 4 marks. Try it first; the hints and our step-by-step solution are below.

Q37 · 4 marks · Case-basedCompetency-basedCarbon and its Compounds

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. Answer the following questions:

  1. (a)

    What are hydrocarbons?

    1 mark
  2. (b)

    List two properties by virtue of which carbon can form a large number of compounds.

    1 mark
  3. (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.

    2 marks

  4. OR

    (c)

    (ii) What are structural isomers? Write the structures of two isomers of butane ().

    2 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/5/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

The name 'hydro-carbon' tells you which elements are present.

Hint 2

Think of carbon's valency and its ability to bond with itself.

Hint 3

For (c), recall that acid + alcohol gives an ester; for isomers, try arranging four carbons in a straight chain and then as a branched chain.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (a) Hydrocarbons are compounds made up of only carbon and hydrogen, e.g. methane () and ethane ().

    1 mark

  2. (b) Carbon forms a large number of compounds because of:

    • Catenation: it can link with other carbon atoms to form long chains, branched chains and rings.
    • Tetravalency: it has a valency of four, so it can bond with four other atoms of carbon or of other elements.
    1 mark

  3. (c)(i) Functional groups:

    (1) Aldehyde: , i.e.

    (2) Ketone: , i.e. (the carbonyl carbon is bonded to two carbon atoms)

    1 mark

  4. Esterification (an acid acts as the catalyst):

    The products are ethyl ethanoate (an ester) and water.

    1 mark

  5. (c)(ii) Structural isomers are compounds that have the same molecular formula but different structures.

    1 mark

  6. Two isomers of butane, :

    1. n-Butane (straight chain):

    2. Isobutane, or 2-methylpropane (branched chain):

    1 mark

Answer: (a) Compounds of only C and H; (b) Catenation and tetravalency; (c)(i) Aldehyde –CHO, ketone >C=O; CH3COOH + C2H5OH → (acid) CH3COOC2H5 + H2O; (c)(ii) Same molecular formula, different structures; n-butane CH3CH2CH2CH3 and isobutane CH3CH(CH3)CH3

Where the marks are

  • Defines hydrocarbons as compounds of carbon and hydrogen only (1 mark)
  • Names tetravalency and catenation (1 mark)
  • Writes –CHO for aldehydes and >C=O for ketones (½ + ½ mark)
  • Writes the balanced esterification equation with the acid catalyst (1 mark)
  • Defines structural isomers (1 mark)
  • Draws the structures of n-butane and isobutane (½ + ½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Carbon and its Compounds, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 31/5/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.