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Answer the following. (Science 2026 31/2/1 Q29b)

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

CBSE Class 10 Science 2026: question 29(b)

Set in the CBSE Class 10 board exam of 2026, paper 31/2/1, 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

Answer the following.

  1. (i)

    Write the structural formula of benzene.

    1 mark
  2. (ii)

    State the reason why carbon can neither form cation nor anion.

    1 mark
  3. (iii)

    What type of bond is formed between carbon and hydrogen ?

    1 mark
  4. (iv)

    How is ethanol converted to ethanoic acid ?

    1 mark
  5. (v)

    Complete the following chemical equation :

    1 mark

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

Benzene is a cyclic compound with six carbons and three double bonds.

Hint 2

Think about energy needed to lose four electrons and the ability of six protons to hold extra electrons.

Hint 3

Converting an alcohol to an acid is oxidation; an ester with NaOH is saponification.

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) Benzene, , is a hexagonal ring of six carbon atoms with alternate single and double bonds (three C=C). Each carbon carries one H atom. Either resonating structure is acceptable.

    1 mark

  2. (ii) Forming needs removal of four electrons, which requires a very large amount of energy. Forming is not possible because a nucleus with six protons cannot hold ten electrons.

    1 mark

  3. (iii) A covalent bond, formed by sharing a pair of electrons.

    1 mark

  4. (iv) Ethanol is oxidised by alkaline or acidified on heating:

    1 mark

  5. (v)

    This is saponification; the products are sodium ethanoate and ethanol.

    1 mark

Answer: (i) Six-carbon hexagonal ring with alternate single/double bonds; (ii) energy needed to lose 4e⁻ is too high, and 6 protons cannot hold 10 electrons; (iii) Covalent; (iv) Oxidation with alkaline KMnO₄/acidified K₂Cr₂O₇; (v) CH₃COONa + C₂H₅OH

Where the marks are

  • Correct structure of benzene (1 mark)
  • Reasons for no C⁴⁺ and no C⁴⁻ (1 mark)
  • Covalent bond (1 mark)
  • Oxidation using alkaline KMnO₄ or acidified K₂Cr₂O₇ (1 mark)
  • Products sodium ethanoate and ethanol (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 31/2/1: 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.