Elements P and Q form two types of non-volatile, non-ionizable compounds PQ and PQ_2$PQ_{2}$. When 1 g of PQ is dissolved in 50 g of solvent ‘A’. Delta T_b$\Delta T_{b}$ was 1.176 K while when 1 g of PQ_2$PQ_{2}$ is dissolved in 50 g of solvent ‘A’, Delta T_b$\Delta T_{b}$ was 0.689 K. (K_b$K_{b}$ of ‘A’ = 5text K kg mol^-1$5\text{ K kg mol}^{-1}$). The molar masses of elements P and Q (in textg mol^-1$\text{g mol}^{-1}$) respectively, are :