${\mathrm{C}}_6{\mathrm{H}}_6\underset{350\mathrm{K}}{\overset{{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}\mathrm{A}\underset{\mathrm{fusion}}{\overset{\mathrm{Alkali}}{\to }}\mathrm{B}\underset{{\mathrm{H}}_2\mathrm{O}}{\overset{{\mathrm{Br}}_2}{\to }}\mathrm{C}$  In the above sequence, C is

benzene sulphonic acid forms sodium phenate, which forms phenol which on bromination gives tribromoderivatives${\mathrm{C}}_6{\mathrm{H}}_6\underset{350\mathrm{K}}{\overset{{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}\mathrm{benzene} \mathrm{sulphonic} \mathrm{acid}\underset{\mathrm{fusion}}{\overset{\mathrm{Alkali}}{\to }}\mathrm{phenol}\underset{{\mathrm{H}}_2\mathrm{O}}{\overset{{\mathrm{Br}}_2}{\to }}2, 4, 6-\mathrm{Tribromophenol}$