$2.56 \mathrm{g}$ of sulphur in $100 \mathrm{g}$ of ${\mathrm{CS}}_2$ has depression in freezing point $0.010°\mathrm{C}, {\mathrm{K}}_{\mathrm{f}}=0.1°\mathrm{C} {\mathrm{molal}}^{-1}.$  Hence, atomicity of sulphur in ${\mathrm{CS}}_2$ is

In what ratio of volumes $0.4 \mathrm{M} \mathrm{HCl}$ and $0.9 \mathrm{M} \mathrm{HCl}$ are to be mixed such that the concentration of the resultant solution becomes $0.7 \mathrm{M}$?

A mixture of toluene and benzene boils at $100°\mathrm{C}$. Assuming ideal behaviour, the mole fraction of toluene in the mixture is closest to:

[Vapour pressures of pure toluene and pure benzene at $100°\mathrm{C}$ are $0.742$ and $1.800 \mathrm{bar}$, respectively. $1 \mathrm{atm}=1.013 \mathrm{bar}$]