Amines

Step 1: Concept
Primary amines react with Hinsberg reagent (benzene sulphonyl chloride) to form a sulphonamide containing an acidic hydrogen.
Step 2: Analysis
is a primary ( ) amine. It reacts to form N-methyl benzene sulphonamide.
Step 3: Solubility
The resulting sulphonamide has a hydrogen atom attached to Nitrogen, making it acidic and thus soluble in alkali (NaOH).
Step 4: Comparison
Secondary amines form sulphonamides without acidic hydrogen (insoluble in alkali), and tertiary amines do not react.
Final Answer: (A)