Mass of organic compound =0.25 g Mass of AgBr=0.15 g No. of moles of Br= No. of moles of AgBr=1880.15 $\begin{aligned}
& \text { Mass of } \mathrm{Br}=\frac{0.15 \times 80}{188} \mathrm{~g} \
& % \text { of } \mathrm{Br}=\frac{0.15 \times 80 \times 100}{188 \times 0.25} \
& =25.5 % \
& =255 \times 10^{-1} %
\end{aligned}$