100ml  $H_2{O}_2$ is completely oxidized by 50ml. of 0.1N  $KMn{O}_4$ solution in acidic medium. The strength of hydrogen peroxide is

$\begin{array}{l}{N}_1{V}_1=N_2{V}_2\\ N_1\text{x100=0.1x50}\\ {\text{N}}_1=\frac{5}{100}=0.05\\ {\text{strength of H}}_2{O}_2=\frac{N}{20}or\frac{M}{40}\\ \text{ =0.17}\raisebox{1ex}{$g$}\!\left/ \!\raisebox{-1ex}{$L$}\right.\\ \text{ =1.7\%}\left(\raisebox{1ex}{$W$}\!\left/ \!\raisebox{-1ex}{$V$}\right.\right)\end{array}$