A compound ' X ' with molecular formula $\mathrm{C}_3 \mathrm{H}_9 \mathrm{~N}$ reacts with $\mathrm{C}_6 \mathrm{H}_5 \mathrm{SO}_2 \mathrm{Cl}$ to give a solid, insoluble in alkali. Identify ' X ' and give the IUPAC name of the product. Write the reaction involved.

(a) Illustrate Sandmeyer's reaction with an equation.

(b) Explain, why $$\left(\mathrm{CH}_3\right)_2 \mathrm{NH}$$ is more basic than $$\left(\mathrm{CH}_3\right)_3 \mathrm{~N}$$ in aqueous solution.