Question

Two elements $X$ and $Y$ have atomic mass $75$ and $16$ respectively. They combine to give a compound having $75.8\%$ $X$. The empirical formula of the compound is:

• A. $XY$
• B. $X_{2}Y$
• C. $X_2{Y}_2$
• D. $X_2{Y}_3$

Answer 1

The correct option is D $X_2{Y}_3$

Let the total mass of the compound be $100g$
Then, mass of $X$ would be $75.8g$
Mass of $Y$ would be $24.2g$
Now, moles of $X=\frac{75.8}{75}\approx 1$
moles of $Y=\frac{24.2}{16}\approx 1.5$
Hence the required empirical formula = $X{Y}_{1.5}=X_2{Y}_3$