Question

Vapour density of gas is $11.2\,$ volume occupied by $2.4\,g$ of this at STP will be.
A) $11.2\,L$
B) $2.24\,L$
C) $22.4\,L$
D) $2.4\,L$

Answer 1

We know that, Vapor density is the ratio of the mass of a volume of a gas, to the mass of an equal volume of hydrogen, measured under the standard conditions of temperature and pressure.
$VapourDensity = \dfrac{{Mass\,of\,X\,volume\,of\,gas}}{{Mass\,of\,equal\,volume\,of\,hydrogen}}$

Complete step by step answer:
First, we find the molar mass of a gas.
The molar mass of a gas, at given the vapor density is calculated using the formula:
$Molar{\text{ }}mass{\text{ }} = {\text{ }}2{\text{ }} \times {\text{ }}vapor{\text{ }}density$
Given,
The vapor density of the gas is$11.2$.
Thus, the molar mass of the gas is calculated as,
$Molar{\text{ }}mass{\text{ }} = {\text{ }}\;2{\text{ }} \times {\text{ }}11.2{\text{ }} = {\text{ }}22.4{\text{ }}gm/mole$
Then, we find the number of moles of the gas.
The given amount of the gas is ${\text{24 }}gm$.
Thus the number of moles of the gas is calculated as,
$Number{\text{ }}of{\text{ }}moles{\text{ }} = {\text{ 2}}{\text{.4}}/22.4{\text{ }}mole{\text{ }} = {\text{ }}0.1071{\text{ }}moles$
We know that, At STP, 1 mole of a gas occupies $22.4{\text{ L}}$ of volume. Here, we have about $0.1071\,moles$ of the gas. Thus, the volume occupied by the gas at STP is,
$Volume{\text{ }}occupied{\text{ }} = {\text{ }}0.1071{\text{ }} \times {\text{ }}22.4{\text{ L }} = \;2.4\,L$
Thus, the $24\,g$ of a gas, with a vapor density of $11.2$, will occupy $2.4\,L$ of volume at STP

So, the correct answer is Option D .

Additional Information:
The volume occupied by one mole of substance at a given temperature and pressure is called molar volume. It is usually applied to the gases where the nature of the gas does not affect the volume. The most general example is that the molar volume of gas at standard temperature-pressure condition is equal to $22.4\,L$ for one mole of an ideal gas at temperature equal to $273\,K$ and pressure equal to$1\,atm$.

Note:
Now we discuss the difference between STP and NTP.
Standard temperature and pressure condition is known as STP. The standard temperature value is $0^\circ C$ and the standard pressure value is $100{\text{ }}kPa$ or $1{\text{ }}bar.$ Normal Temperature and Pressure is known as NTP the value of pressure at NTP is $101.325{\text{ }}kPa$ and the temperature at NTP is $20^\circ C$.