JEE Main 2026 — Jan 28, Shift 1 — Chemistry solution

JEE Main2026Jan 28, Shift 1Chemistry

Given below are two statements for the following reaction sequence.

Statement I: Compound 'Z' will give yellow precipitate with NaOI.

Statement II: Compound 'Q' has two different types of 'H' atoms (aromatic : aliphatic) in the ratio 1 : 3.

In the light of the above statements, choose the correct answer from the option given below:

A
Statement I is true but Statement II is false
B
Both Statement I and Statement II are true
C
Statement I is false but Statement II is true
D
Both Statement I and Statement II are false

Solution

X (C $_{9}$ H $_{6}$ Cl $_{2}$ ) is a geminal dichloride (e.g. 2,2-dichloropropane analogue with the third carbon bearing dichloride); NaNH $_{2}$ (excess) performs double dehydrohalogenation to give propyne (Y is methylacetylene, CH $_{3}$ -C $\equiv$ CH).

Statement I: Y + dil. H $_{2}$ SO $_{4}$ /Hg $^{2 +}$ (Kucherov / Markovnikov hydration of a terminal alkyne) gives propan-2-one (acetone, CH $_{3}$ COCH $_{3}$ ), Z. Acetone is a methyl ketone, which gives a yellow iodoform precipitate (CHI $_{3}$ ) on treatment with NaOI. True.

Statement II: Three molecules of propyne cyclotrimerise over red-hot iron tube to give mesitylene (1,3,5-trimethylbenzene), Q (C $_{9}$ H $_{12}$ ). It has 3 equivalent aromatic Hs and 9 equivalent methyl Hs, so the aromatic : aliphatic H ratio is 3 : 9 = 1 : 3. True.

$∴$ Both statements are true. Option (2).

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