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Give the reaction of… (Class 12 Chemistry 2023, Q25)

questionbuddy.in/q/cbse-12-chemistry-2023-56-5-1-q25-give-reaction-glucose-hydrogen-cyanide

ChemistryCBSE Class 12 · Board exam 2023, set 56/5/1 · 2 marks · Very short answer

CBSE Class 12 Chemistry 2023: question 25

Set in the CBSE Class 12 board exam of 2023, paper 56/5/1, 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

Give the reaction of glucose with hydrogen cyanide. Presence of which group is confirmed by this reaction ?

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 56/5/1.

Hints

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

Hint 1

HCN undergoes nucleophilic addition with which type of functional group?

Hint 2

Write the open-chain glucose and add H and CN across the C=O.

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. Glucose adds HCN across its C=O group to form a cyanohydrin:
    (glucose cyanohydrin)

    1 mark

  2. This addition reaction confirms the presence of a carbonyl group (>C=O), which in glucose is the aldehydic (–CHO) group.

    1 mark

Answer: Glucose cyanohydrin formed; confirms carbonyl (aldehyde) group

Where the marks are

  • Correct equation forming glucose cyanohydrin (1 mark)
  • Presence of carbonyl/aldehydic group confirmed (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 56/5/1: 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.