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Attempt either option… (Class 10 Science SQP 2026-27, Q26A)

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ScienceCBSE Class 10 · Sample paper, session 2026-27 · 3 marks · Short answer

CBSE Class 10 Science sample paper 2026-27: question 26(A)

From the official CBSE sample question paper for 2026-27, section B, question 26(A), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q26(A) · 3 marks · Short answerCompetency-basedCarbon and its Compounds

Attempt either option A or B. A. An organic compound "X" with formula is used to blend with petrol in order to reduce the dependence on fossil fuels and lower down the harmful emissions from the cars. It is also used as a solvent in medicines such as tincture iodine, cough syrups and many tonics. (i) Draw the electron dot structure of "X". (ii) Write the name and formula of the next homologue of "X". (iii) Write the reaction of "X" with acetic acid to form a sweet smelling substance.

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2026-27.

Hints

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

Hint 1

Which alcohol is blended with petrol and used in tinctures and cough syrups?

Hint 2

Successive homologues differ by a unit.

Hint 3

An acid and an alcohol react, with conc. sulphuric acid as catalyst, to give a sweet-smelling ester.

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 = ethanol, (structure ). In the electron dot structure:

    • the two carbon atoms share one electron pair between them;
    • the first C shares three electron pairs with three H atoms;
    • the second C shares two electron pairs with two H atoms and one pair with O;
    • O shares one pair with H and carries two lone pairs.

    Each C and O has an octet and each H has a duplet.

    1 mark

  2. (ii) The next homologue differs by one unit. It is propanol, ().

    1 mark

  3. (iii) Esterification gives the sweet-smelling ester ethyl ethanoate:

    1 mark

Answer: (i) Electron dot structure of ethanol (O with two lone pairs); (ii) Propanol, ; (iii)

Where the marks are

  • Correct electron dot structure of ethanol showing all shared pairs and the lone pairs on O (1 mark)
  • Names propanol (0.5 mark) and gives the formula (0.5 mark)
  • Balanced esterification equation with conc. (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 paperSample paper 2026-27: 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.