Question

A compound has the molecular formula $X_4{O}_6$. If $10$ g of $X_4{O}_6$ has $5.72$ g X, then the atomic mass of X is :

• A. $32$ amu
• B. $64$ amu
• C. $67$ amu
• D. $98$ amu

Answer 1

The correct option is A $32$ amu

Molecular weight of $X_4{O}_6=(4a+96)$

$\because (4a+96)g$ $X_4{O}_6$ contains $X=4a$ g

$\therefore 10$g of $X_4{O}_6$ contains X$=\frac{4a\times 10}{4a+96}$

$5.72=\frac{4a\times 10}{4a+96}$

$22.88a+549.12=40a$

$17.12a=549.12$

$a=32.07$amu.