What happens when acetic acid is treated with ${\mathrm{NH}}_4\mathrm{OH}$ and the product is then heated?

Identify A and B in the following equation:

${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH} \underset{\mathrm{conc}.{\mathrm{H}}_2{\mathrm{SO}}_4}{\overset{\mathrm{conc}.{\mathrm{HNO}}_3}{\to }} \mathrm{A} \underset{∆}{\overset{\mathrm{NaOH}/\mathrm{CaO}}{\to }} \mathrm{B}$

Identify A and B in the following equation:

${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH} \stackrel{{\mathrm{SOCl}}_2}{\to } \mathrm{A} \underset{\mathrm{Pd}/{\mathrm{BaSO}}_4}{\overset{{\mathrm{H}}_2}{\to }} \mathrm{B}$