Question

A certain compound has molecular formula $X_4{O}_6$. If $10$ g of compound contains $5.62$ g of $X$, the atomic weight of $X$ is nearly:

• A. $62$
• B. $48$
• C. $31$
• D. $37$

Answer 1

The correct option is C $31$

$10$ g of a compound contains $5.62$ g of $X$.

Hence, the percentage of $X$ is $100\times \frac{5.62}{10}=56.2$.

Let the atomic weight of $X$ be $x$ g/mol. The atomic weight of oxygen is $16$ g/mol.

Percentage of $X=\frac{4x}{4x+6\times 16}\times 100=\frac{200x}{2x+48}$.

Thus, $\frac{200x}{2x+48}=56.2$

$x=31$.

Hence, option C is correct.