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In which of the following… (Class 12 Chemistry 2024, Q9)

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ChemistryCBSE Class 12 · Board exam 2024, set 56/5/1 · 1 mark · MCQ

CBSE Class 12 Chemistry 2024: question 9

Set in the CBSE Class 12 board exam of 2024, paper 56/5/1, section A, question 9, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q9 · 1 mark · MCQHaloalkanes and Haloarenes

In which of the following molecules, C atom marked with asterisk is chiral ?

  1. (A)I, II, III
  2. (B)I, II, III, IV
  3. (C)II, III, IV
  4. (D)I, III, IV

Figure in the paper: Four structures, each with a central starred C atom with wedge/dash bonds. (I) C* bonded to H (top), CH3 (wedge, left), Br (dash, right), Cl (dash, bottom). (II) C* bonded to D (top), I (wedge, left), Br (dash, right), Cl (bottom). (III) C* bonded to D (top), HO (wedge, left), CH2CH3 (dash, right), CH3 (bottom). (IV) C* bonded to H (top), D (wedge, left), CH3 (dash, right), CH3 (bottom). See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 56/5/1.

Hints

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

Hint 1

A chiral carbon must carry four different groups.

Hint 2

Check each structure for repeated groups; H and D count as different.

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. In I (H, CH3, Br, Cl), II (D, I, Br, Cl) and III (D, OH, C2H5, CH3), the starred carbon carries four different groups, so each is chiral.

  2. In IV the starred carbon carries two CH3 groups, so it is not chiral. The answer is I, II, III, option (A).

    1 mark

Answer: I, II, III, option (A)

Where the marks are

  • Recognises that IV has two identical CH3 groups and so is not chiral (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Haloalkanes and Haloarenes, one at a time, marked against the answer key and marking points.Back to the full paper2024 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.