$\mathbf { 1 3 7 ~ m g }$ of paranitro toluene react with $\mathrm { Sn } + \mathrm { HCl }$ form A which react with $\mathbf { A c O } _ { \mathbf { 2 } }$ form B and B react with Bromine in presence of acetic acid form C . find out mass of C in mg .