The major products A and B from the following reactions are:

The major product formed in the following reaction is

Compound $$\mathrm{P}$$ is neutral, $$\mathrm{Q}$$ gives effervescence with $$\mathrm{NaHCO}_{3}$$ while $$\mathrm{R}$$ reacts with Hinsbergs reagent to give solid soluble in $$\mathrm{NaOH}$$. Compound $$\mathrm{P}$$ is

In the following reaction, 'A' is