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Mohan heated ethanol with a… (Class 10 Science 2026, Q29b)

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ScienceCBSE Class 10 · Board exam 2026, set 31/1/1 · 5 marks · Long answer

CBSE Class 10 Science 2026: question 29(b)

Set in the CBSE Class 10 board exam of 2026, paper 31/1/1, section B, question 29(b), for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q29(b) · 5 marks · Long answerCarbon and its Compounds

Mohan heated ethanol with a compound 'X' in the presence of a few drops of conc. H2SO4 and observed a sweet smelling compound 'Y' is formed. When 'Y' is treated with sodium hydroxide it gives back ethanol and a compound 'Z'.

  1. (i)

    Identify 'X', 'Y' and 'Z'.

    0 marks
  2. (ii)

    Write the role of conc. H2SO4 in the reaction.

    0 marks
  3. (iii)

    Write the chemical equations involved and name the reactions.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/1/1.

Hints

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

Hint 1

Sweet-smelling compounds are esters.

Hint 2

An ester comes from an alcohol and a carboxylic acid.

Hint 3

A base splits the ester back into an alcohol and the sodium salt of the acid.

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) X is ethanoic acid (acetic acid), , because it reacts with ethanol to give a sweet-smelling compound.

    ½ mark

  2. (i) Y is ethyl ethanoate, an ester, .

    ½ mark

  3. (i) Z is sodium ethanoate (sodium acetate), .

    ½ mark

  4. (ii) Concentrated acts as a catalyst and dehydrating agent: it removes the water formed and speeds up the reaction.

    ½ mark

  5. (iii)

    1 mark

  6. (iii) This reaction is called esterification.

    ½ mark

  7. (iii)

    1 mark

  8. (iii) This reaction is called saponification.

    ½ mark

Answer: (i) X = CH₃COOH, Y = CH₃COOC₂H₅, Z = CH₃COONa; (ii) catalyst/dehydrating agent; (iii) esterification and saponification (equations shown)

Where the marks are

  • Identifies X, Y and Z (½ mark each)
  • Role of conc. H₂SO₄ (½ mark)
  • Esterification equation (1 mark) and name (½ mark)
  • Saponification equation (1 mark) and name (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 paper2026 board paper, set 31/1/1: 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.