Question

After an experiment,$56$ litre of a gas at STP was found to have a mass of $110$ grams.The gas is:

• A. $O_2$
• B. $C{O}_2$
• C. $N_2$
• D. $Ar$

Answer 1

The correct option is B $C{O}_2$

At S.T.P, 1 mole of any gas occupies a volume of $22.4L$.
Volume of gas is $56L$
The number of moles of gas $=\frac{56L}{22.4L}=2.5$ mol.
The mass of gas is 110 g.

The molecular mass will be $\frac{110g}{2.5mol}=44g/mol$

This is molecular mass of $C{O}_2$ gas.

$12+2\left(16\right)=12+32=44$

Hence, the gas is $C{O}_2$.