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(i) How would you name the… (Class 10 Science 2026, Q29B)

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ScienceCBSE Class 10 · Board exam 2026, set 31/4/1 · 5 marks · Short answer

CBSE Class 10 Science 2026: question 29(B)

Set in the CBSE Class 10 board exam of 2026, paper 31/4/1, 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 · Short answerCarbon and its Compounds

(i) How would you name the following:
I.
II.
(ii) When ethanol reacts with ethanoic acid in the presence of conc. , a substance with sweet smell is produced. Answer the following:
I. State the class of compounds to which the sweet smelling compounds belong.
II. Write the chemical equation for the reaction.
(iii) Why soaps do not produce foam with hard water?

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/4/1.

Hints

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

Hint 1

Count the carbon atoms and identify the functional group or bond for the suffix.

Hint 2

An acid and an alcohol react to give which class of compound?

Hint 3

Which ions make water hard, and what do they form with soap?

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) I. has three carbons and an aldehyde group: Propanal.

    1 mark

  2. II. has three carbons and a triple bond: Propyne.

    1 mark

  3. (ii) I. The sweet-smelling compounds are esters (ester group, ).

    1 mark

  4. II. Esterification:

    The product is ethyl ethanoate.

    1 mark

  5. (iii) Hard water contains calcium and magnesium salts. Soap reacts with them to form an insoluble precipitate called scum, so the soap is wasted and little foam forms.

    1 mark

Answer: (i) I. Propanal; II. Propyne. (ii) I. Esters; II. (conc. HSO). (iii) Soap forms insoluble scum with Ca/Mg salts.

Where the marks are

  • Names propanal (1 mark)
  • Names propyne (1 mark)
  • States that the products are esters (1 mark)
  • Writes the esterification equation (1 mark)
  • Explains scum formation with Ca and Mg salts (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 paper2026 board paper, set 31/4/1: 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.