JEE Chemistry 2026 Question with Solution

Given: The molecular formula of $X$ is $C_6H_7N$. On treatment with benzenesulphonyl chloride, $X$ gives a compound $Z$ soluble in alkali.

Find: The number of different hydrogen atoms present in $Z$.

The Hinsberg test is crucial: a primary amine forms an alkali-soluble sulfonamide, a secondary amine forms an alkali-insoluble sulfonamide, and a tertiary amine does not react.

From the molecular formula, $X$ corresponds to aniline.

On treatment with benzenesulphonyl chloride $\mathrm{C_6H_5SO_2Cl}$, aniline undergoes the Hinsberg reaction to form sulphonamide:

The product $Z$ is soluble in alkali due to the presence of an acidic $N-H$ proton, confirming that $X$ is a primary amine.

Now count the different types of hydrogen atoms in $Z$:

• One type of hydrogen due to the $N-H$ proton.
• The aromatic protons in the phenyl rings appear in four distinct chemical environments due to symmetry and substitution effects.

Therefore, the number of different hydrogen atoms in $Z$ is $5$. The correct option is A.