JEE Main 2024 · 9 April · evening · Single correct · +4 / −1
Match List I with List II
Choose the correct answer from the options given below:
| LIST I (Test) | LIST II (Observation) | ||
|---|---|---|---|
| A. | Br₂ water test | I. | Yellow orange or orange red precipitate formed |
| B. | Ceric ammonium nitrate test | II. | Reddish orange colour disappears |
| C. | Ferric chloride test | III. | Red colour appears |
| D. | 2, 4 - DNP test | IV. | Blue, Green, Violet or Red colour appear |
- (a) A-II, B-III, C-IV, D-I
- (b) A-III, B-IV, C-I, D-II
- (c) A-I, B-II, C-III, D-IV
- (d) A-IV, B-I, C-II, D-III
Answer and solution
Answer (a) A-II, B-III, C-IV, D-I
Solution
Chemistry ma’am · 3 steps
Link each test to the group it detects, and the colour change follows from that.
- Think group first. Each test in List I detects one functional group. Name the group first, then recall what the student sees in the test tube.
Test Detects What you see Match Br₂ water C=C or C≡C (unsaturation) Br₂ adds across the multiple bond, so its reddish orange colour disappears A-II Ceric ammonium nitrate Alcohols The yellow reagent turns red B-III Neutral FeCl₃ Phenols (enols) Blue, green, violet or red colour from an iron complex C-IV 2,4-DNP Aldehydes and ketones Yellow orange or orange red precipitate of the 2,4-dinitrophenylhydrazone D-I - Avoid the mix-up. Both CAN and FeCl₃ give colours. CAN gives a single red colour with alcohols. FeCl₃ gives a range of colours because different phenols form different iron complexes.
- So. The matching is A-II, B-III, C-IV, D-I, which is option (a).
The idea to keep. Learn these tests as pairs: bromine water fades for unsaturation, CAN turns red for alcohols, FeCl₃ gives violet-type colours for phenols, and 2,4-DNP gives an orange precipitate for carbonyls.
Answer from the NTA final answer key. Solution by PrepWiser.