Chemistry - Mole Concept Question with Solution | TestHub

At STP, the molar volume of an ideal gas is $22.4{\text{ dm}}^3\text{/mol}$.

Number of moles of the gas, $n=\frac{V}{22.4}=\frac{4.48}{22.4}=0.2\text{ mol}$

Molar mass of the gas, $M=\frac{m}{n}=\frac{5.6}{0.2}=28\text{ g/mol}$

Checking the molar masses of the given options:
Molar mass of ${\mathrm{Cl}}_2=2\times 35.5=71\text{ g/mol}$
Molar mass of ${\mathrm{O}}_2=2\times 16=32\text{ g/mol}$
Molar mass of ${\mathrm{N}}_2=2\times 14=28\text{ g/mol}$
Molar mass of ${\mathrm{CH}}_4=12+4\times 1=16\text{ g/mol}$

The calculated molar mass matches that of ${\mathrm{N}}_2$.

Answer: ${\mathrm{N}}_2$