JEE Chemistry 2025 Question with Solution

Given: Five statements about amines, carbylamine test, diazotisation, and Hinsberg’s reagent are given.

Find: Which statements are correct and hence the correct option.

Analyze each statement one by one:

1. (A) Primary amines do not give diazonium salts when treated with $\text{NaNO}_2$ in acidic condition.

This is incorrect because aromatic primary amines form diazonium salts under these conditions. Therefore, (A) is false.

2. (B) Aliphatic and aromatic primary amines on heating with $\text{CHCl}_3$ and ethanolic $\text{KOH}$ form carbylamines.

This is the carbylamine reaction, which is given by primary amines. Therefore, (B) is true.

3. (C) Secondary and tertiary amines also give carbylamine test.

This is incorrect because the carbylamine test is specific to primary amines only. Therefore, (C) is false.

4. (D) Benzenesulfonyl chloride is known as Hinsberg’s reagent.

This statement is correct. Therefore, (D) is true.

5. (E) Tertiary amines react with benzenesulfonyl chloride very easily.

This is incorrect because tertiary amines do not react with benzenesulfonyl chloride under mild conditions in the Hinsberg test. Therefore, (E) is false.

So, the correct statements are (B) and (D) only.

The correct option is B.

Given: Statements (A) to (E) are based on reactions of amines.

Find: The combination of correct statements.

Step 1: Check diazotisation.

Primary aromatic amines react with $\text{NaNO}_2$ in acidic medium to form diazonium salts, whereas aliphatic diazonium compounds are unstable. Hence statement (A) is incorrect.

Step 2: Check carbylamine test.

Primary amines on heating with $\text{CHCl}_3$ and ethanolic $\text{KOH}$ give isocyanides or carbylamines. Hence statement (B) is correct.

Only primary amines respond to this test, so statement (C) is incorrect.

Step 3: Check Hinsberg reagent.

Benzenesulfonyl chloride is called Hinsberg’s reagent, so statement (D) is correct.

Tertiary amines do not react with benzenesulfonyl chloride because they do not have the required N–H bond. Hence statement (E) is incorrect.

Conclusion: The true statements are (B) and (D) only, so the correct option is B.