Question

Suppose the elements $X$ and $Y$ combine to form two compounds $XY_2$ and $X_3Y_2$. When $0.1$ mole of $XY_2$ weighs $10\, g$ and $0.05$ mole of $X_3Y_2$ weighs $9\, g$, the atomic weights of $X$ and $Y$ are

• A. 40, 30
• B. 60, 40
• C. 20, 30
• D. 30 , 20

Answer 1

Answer: (A)

40, 30

Answer 2

For $X{{Y}_{2}}$
$?? 0.1 mole$X{{Y}{2}}$$ ??10 g ??$1 mole$X{{Y}{2}}$$??100 g $$=X+2Y=100 $.......(i) For${{X}{3}}{{Y}{2}}$$ \because ; 0.05$mole${{X}{3}}{{Y}{2}} $$\because ; 9 g$$ \therefore$1 mole${{X}{3}}{{Y}{2}} ??180 g$(ii) On solving,$X = 40$And$Y = 30$