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(a) Write chemical reaction… (Class 12 Chemistry 2023, Q25)

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ChemistryCBSE Class 12 · Board exam 2023, set 56/1/1 · 2 marks · Very short answer

CBSE Class 12 Chemistry 2023: question 25

Set in the CBSE Class 12 board exam of 2023, paper 56/1/1, section B, question 25, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q25 · 2 marks · Very short answerBiomolecules

(a) Write chemical reaction to show that open structure of D-glucose contains the straight chain.
(b) What type of linkage is responsible for the formation of protein ?

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 56/1/1.

Hints

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

Hint 1

Which reagent reduces all the –OH and –CHO groups of glucose to C–H?

Hint 2

If the product is an unbranched alkane, what does that say about the carbon chain?

Hint 3

Proteins are polyamides of amino acids.

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. (a) On prolonged heating with HI, glucose forms n-hexane. This shows that all six carbon atoms of glucose are linked in a straight chain:
    (n-hexane)

    1 mark

  2. (b) Proteins are formed by peptide linkage (). This is an amide bond between the –COOH of one amino acid and the –NH₂ of the next.

    1 mark

Answer: (a) Glucose + HI (heat) → n-hexane; (b) peptide linkage (–CO–NH–)

Where the marks are

  • Reaction of glucose with HI giving n-hexane (1 mark)
  • Peptide linkage (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Biomolecules, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 56/1/1: 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.