A carbon compound ‘P’ of molecular formula C_2H_6O is found to be neutral when tested with red and blue litmus. A gas that burns with a pop sound is produced when sodium metal reacts with compound ‘P’. (i) Identify the compound ‘P’. (ii) The carbon compound ‘P’ is heated with conc. H_2SO_4 at 443 K to produce compound ‘Q’. (I) Write the chemical equation for the reaction. (II) What is the role of conc. H_2SO_4 in this reaction ? (iii) What is likely to be observed on heating compound ‘P’ with ethanoic acid with an acid as a catalyst ? Write the chemical equation for the reaction.

ScienceCBSE Class 10 · Board exam 2026, set 31/2/1 · 5 marks · Long answer

CBSE Class 10 Science 2026: question 29(a)

Set in the CBSE Class 10 board exam of 2026, paper 31/2/1, section B, question 29(a), for 5 marks. Try it first; the hints and our step-by-step solution are below.

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

A carbon compound ‘P’ of molecular formula $C_{2} H_{6} O$ is found to be neutral when tested with red and blue litmus. A gas that burns with a pop sound is produced when sodium metal reacts with compound ‘P’.

(i)
Identify the compound ‘P’.
1 mark
(ii)
The carbon compound ‘P’ is heated with conc. $H_{2} S O_{4}$ at 443 K to produce compound ‘Q’.
(I) Write the chemical equation for the reaction.
(II) What is the role of conc. $H_{2} S O_{4}$ in this reaction ?
2 marks
(iii)
What is likely to be observed on heating compound ‘P’ with ethanoic acid with an acid as a catalyst ? Write the chemical equation for the reaction.
2 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/2/1.

Hints

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

Hint 1

Which C₂H₆O compound is neutral and gives H₂ with sodium?

Hint 2

Conc. H₂SO₄ at 443 K removes a water molecule.

Hint 3

An alcohol and a carboxylic acid combine to give a fruity-smelling compound.

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.

(i) P is ethanol, $C_{2} H_{5} O H$ ( $C H_{3} C H_{2} O H$ ). It is neutral to litmus and reacts with sodium to give $H_{2}$ , which burns with a pop.
1 mark
(ii)(I) $C H_{3} C H_{2} O H hot conc. H_{2} S O_{4} 443 K C H_{2} = C H_{2} + H_{2} O$
Q is ethene.
1 mark
(ii)(II) Concentrated $H_{2} S O_{4}$ acts as a dehydrating agent, removing water from ethanol.
1 mark
(iii) A sweet-smelling substance, an ester (ethyl ethanoate), is formed. This reaction is esterification.
1 mark
(iii) $C H_{3} C O O H + C H_{3} C H_{2} O H acid C H_{3} C O O C H_{2} C H_{3} + H_{2} O$
1 mark

Answer: (i) Ethanol; (ii) C₂H₅OH → CH₂=CH₂ + H₂O (hot conc. H₂SO₄, 443 K), H₂SO₄ is dehydrating agent; (iii) Sweet-smelling ester formed: CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

Where the marks are

Identifies P as ethanol (1 mark)
Equation for dehydration to ethene (1 mark)
Role: dehydrating agent (1 mark)
Observation: sweet-smelling ester (1 mark)
Esterification equation (1 mark)

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Chapter: Carbon and its Compounds (notes, formulas, where marks are lost and every past question)

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CBSE Class 10 Science 2026: question 29(a)

Hints

Step-by-step solution

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