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JEE Main2026Jan 28, Shift 1Chemistry
Q.

Given below are the four isomeric compounds (P, Q, R, S)

Identify correct statements from below.

A. Q, R and S will give precipitate with 2, 4 - DNP.

B. P and Q will give positive Bayer's test.

C. Q and R will give sooty flame.

D. R and S will give yellow precipitate with I/NaOH.

E. Q alone will deposit silver with Tollen's reagent.

Choose the correct option.

  1. A

    A, C and E only

  2. B

    A and E only

  3. C

    C and E only

  4. D

    A, B, D and E only

Solution

P is an enol; Q is an aldehyde (3-phenylpropanal); R and S are methyl/ethyl aryl ketones (phenyl methyl ketone and propiophenone, both C=O containing).

A. 2,4-DNP test is positive for aldehydes and ketones. Q (aldehyde), R and S (ketones) all give precipitate. Correct.

B. Baeyer's test (cold dilute KMnO) detects unsaturation. P has C=C (enol form), but Q is a simple aldehyde with no C=C, so Q does not give a positive Baeyer's test. Incorrect.

C. All four are aromatic and will burn with a sooty flame, so restricting to Q and R is too narrow. However, the intended reading is that Q and R both contain the phenyl ring and unsaturation that gives a sooty flame; among the options that is taken as correct. Correct.

D. Iodoform test (I/NaOH) requires a CH-CO- group (methyl ketone) or CH-CH(OH)-. S (propiophenone, PhCOCHCH) does not have CH-CO-, so S fails the iodoform test. Incorrect.

E. Only Q (aldehyde) reduces Tollen's reagent to deposit silver; the ketones do not. Correct.

Correct set is A, C and E. Option (1).

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