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Friday, 9 October

JEE Main 2025 · ChemistryMultiple choiceSingle correctMediumConceptual

JEE Main 8 April 2025, Shift 2, Chemistry Q70

Question 70 of 75 in this shift, Chemistry question 20 of 25, Section A.

[structure: valine, H2N−CH(CH(CH3)2)−COOH\mathrm{H_2N-CH(CH(CH_3)_2)-COOH}; an arrow from it splits into A at pH = 2 and B at pH = 10] Choose the correct option for structures of A and B, respectively

The figure, in words

Valine, H2N-CH(CH(CH3)2)-COOH, drawn with a downward arrow; a branching arrow leads to A at pH = 2 (left) and B at pH = 10 (right).
  1. (1)H3N+−CH(CH(CH3)2)−COO−\mathrm{H_3\overset{+}{N}-CH(CH(CH_3)_2)-COO^-} and H3N+−CH(CH(CH3)2)−COOH\mathrm{H_3\overset{+}{N}-CH(CH(CH_3)_2)-COOH}
  2. (2)H3N+−CH(CH(CH3)2)−COOH\mathrm{H_3\overset{+}{N}-CH(CH(CH_3)_2)-COOH} and H2N−CH(CH(CH3)2)−COO−\mathrm{H_2N-CH(CH(CH_3)_2)-COO^-}Official answer
  3. (3)H2N−CH(CH(CH3)2)−COO−\mathrm{H_2N-CH(CH(CH_3)_2)-COO^-} and H3N+−CH(CH(CH3)2)−COOH\mathrm{H_3\overset{+}{N}-CH(CH(CH_3)_2)-COOH}
  4. (4)H2N−CH(CH(CH3)2)−COO−\mathrm{H_2N-CH(CH(CH_3)_2)-COO^-} and H3N+−CH(CH(CH3)2)−COO−\mathrm{H_3\overset{+}{N}-CH(CH(CH_3)_2)-COO^-}

Official answer

Option 2

NTA final key.

Chapter
Biomolecules
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.