Question

The sulphate of a metal $M$ contains 9.87% of $M$. This sulphate is isomorphous with $ZnS{O}_4.7H_{2}O$. The atomic weight of $M$ is

• A. $40.3$
• B. $36.3$
• C. $24.3$
• D. $11.3$

Answer 1

Answer: (C)

As the given sulphate is isomorphous with $ZnS{O}_4.7H_{2}O$ its formula Would be $MS{O}_4.7H_{2}O.m$ is the atomic weight of $M$ molecular weight of $MS{O}_4.7H_{2}O$
$=m+32+64+126=m+222$
Hence % of $M=\frac{m}{m+222}\times 100=9.87$(given) or
$100m=9.87m+222\times 9.87or90.13m=222\times 9.87$
or $m=\frac{222\times 9.87}{90.13}=24.3$