Question

The vapour density of a chloride of an element is $39.5$. The Equivalent weight of the element is $3.82$. The atomic weight of the element is (to the nearest integer) :

Answer 1

Molecular weight of metal chloride $\left(MC{l}_x\right)=M+x\times 35.5$ $=2\times V.D=2\times 39.5$ $=79.0$
$MW=EW\times x$
Valency of metal $=x$
Atomic weight of element $=EW\times x$
$MC{l}_x=3.82\times x+x\times 35.5=79$
$x=\frac{79}{3.82+35.5}\approx 2$
Atomic weight $=EW\times x=3.82\times 2=7.64$
So, nearest integer is $8$.