Question

The molality of a $10 \%$ (v/v) solution of di-bromine solution in $CCl _4$ (carbon tetrachloride) is ' $x$ ' $x=$____ $\times 10^{-2} M$ (Nearest integer) [Given : molar mass of $Br _2=160 \,g \,mol ^{-1}$ atomic mass of $C =12\, g \,mol ^{-1}$ atomic mass of $Cl =355\, g\, mol ^{-1}$ density of dibromine $=32 \,g\, cm ^{-3}$ density of $CCl _4=16\, g \,cm ^{-3}$ ]

Answer 1

The correct answer is 139.
( 10ml solute in 90ml solvent
mass of solute =10×3.2=32g
mass of solvent =90×1.6g
m=160×90×1.632×1000​=1.388
m−138.8×10−2−139