Compound A `(C_(3)H_(9)N)` reacts with benzene sulphonyl chloride to form a solid insoluble in alkali. The structure of compound A is

Explanation

Since `A(C_(3)H_(9)N)` reacts with benzenesulphonyl chloride to give a solid insoluble in alkali, (A) must be a `2^(@)` amine: i.e., `CH_(3)-CH-CH_(2)CH_(3)` (ethylmethylamine).