116 mg of a compound on vapourization in a Victor Meyer's apparatus displaces 44.8 ml of air measured at STP. The molecular weight of the compounds is

$$\begin{gathered} 116 \mathrm{mg} \mathrm{compounds} \mathrm{means} 116 \times {10}^{-3} \mathrm{gm} \mathrm{compound} \mathrm{since} 1 \mathrm{mg} \mathrm{contain} {10}^{-3} \mathrm{gm} \\ \mathrm{Mol}. \mathrm{wt}. \mathrm{of} \mathrm{compound} = \frac{\mathrm{mass} \mathrm{of} \mathrm{the} \mathrm{substance}}{\mathrm{volume} \mathrm{of} \mathrm{the} \mathrm{vapour} \mathrm{at} \mathrm{S}.\mathrm{T}.\mathrm{P}.}\times 22400 \\ = \frac{116 \times {10}^{-3}}{44.8} \times 22400 = 57.99\% \mathrm{or} 58\%. \end{gathered}$$