Question

A gas has a vapour density $11.2$. The volume occupied by $1g$ of the gas at STP is:

Answer 1

We know that:
$\text{vapour density}=\text{molar mass}/2$

Molar mass of a gas $=2\times 11.2=22.4g$

We know that at STP one mole of gas occupies $22.4L$

So $22.4g$ of the given gas occuies $22.4L$ .
Volume occupied by $1g$ compound at STP $=\frac{22.4}{22.4}=1L$