Question

The vapour density of gas $A$ is four times that of $B$. If molecular mass of $B$ is $M$, then molecular mass of $A$ is:

• A. $M$
• B. $4M$
• C. $\frac{M}{4}$
• D. $2M$

Answer 1

Answer: (B)

Molecular mass of $B=M$

V.D. of $B=M/2$

V.D. of $A=4\times$ V.D. of $B$

$4\times \frac{M}{2}=2M$

Molecular mass of $A=2\times 2M=4M$