question_answer

Two elements A and B form compounds having molecular formulae \[A{{B}_{2}}\] and \[A{{B}_{4'}}\], when dissolved in 20 g of \[{{C}_{6}}{{H}_{6}},1\,\,\,g\,\,A{{B}_{2}}\] lowers the freezing point by 2.3 K whereas 1.0 g of \[A{{B}_{4}}\]lowers it by 1.3 K. The molal depression constant for benzene is \[5.1\text{ }K\text{ }kg\text{ }mo{{l}^{-l}}\] The atomic masses of A and B are, respectively

A)  \[A=25.59\,\,g;B=42.64g\]

B)  \[A=31.72\,\,g;B=42.02g\]

C)  \[A=13.11g;B=24.25g\]

D)  \[A=19.17g;B=35.01g\]