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(i) A compound 'A' with a… (Class 10 Science 2023, Q34a)

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ScienceCBSE Class 10 · Board exam 2023, set 31/6/1 · 5 marks · Long answer

CBSE Class 10 Science 2023: question 34(a)

Set in the CBSE Class 10 board exam of 2023, paper 31/6/1, section D, question 34(a), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q34(a) · 5 marks · Long answerCarbon and its Compounds

(i) A compound 'A' with a molecular formula of reacts with a base to give salt and water. Identify 'A', state its nature and the name of the functional group it possesses. Write chemical equation for the reaction involved.

(ii) When the above stated compound 'A' reacts with another compound 'B' having molecular formula in the presence of an acid, a sweet smelling compound 'C' is formed.
(1) Identify 'B' and 'C'.
(2) State the role of acid in this reaction.
(3) Write chemical equation for the reaction involved.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/6/1.

Hints

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

Hint 1

A compound that reacts with a base to give salt and water is an acid. Which organic acid has 2 carbon atoms?

Hint 2

C₂H₆O is a common alcohol. An acid plus an alcohol gives a sweet-smelling substance.

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. (i) A is ethanoic acid (acetic acid), .

    ½ mark

  2. Its nature is acidic.

    ½ mark

  3. Its functional group is the carboxylic acid group, .

    ½ mark

  4. Reaction with a base: (sodium ethanoate + water).

    1 mark

  5. (ii)(1) B is ethanol, .

    ½ mark

  6. C is the ester ethyl ethanoate, .

    ½ mark

  7. (ii)(2) The acid (conc. ) acts as a catalyst.

    ½ mark

  8. (ii)(3) Esterification:

    1 mark

Answer: (i) A = ethanoic acid, acidic, –COOH; CH₃COOH + NaOH → CH₃COONa + H₂O. (ii) B = ethanol, C = ethyl ethanoate (ester); acid is a catalyst; CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

Where the marks are

  • Identifies A as ethanoic acid (½ mark)
  • Nature acidic (½ mark)
  • Functional group –COOH (½ mark)
  • Neutralisation equation (1 mark)
  • B = ethanol (½ mark)
  • C = ester/ethyl ethanoate (½ mark)
  • Acid acts as catalyst (½ mark)
  • Esterification equation (1 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 paper2023 board paper, set 31/6/1: 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.