Question

The mass of $O$ atoms present in $5.675$ litre of carbon dioxide at STP is:

• A. $32\text{g}$
• B. $16\text{g}$
• C. $8\text{g}$
• D. $24\text{g}$

Answer 1

The correct option is C $8\text{g}$

Using the interconversion of mole-volume relationship,
We have, the number of moles,
$n=\frac{\text{Volume of gas (at STP)}}{22.7}$
$\Rightarrow n=\frac{5.675}{22.7}=0.25$ mol
$2$ moles of $O$ atoms are present in one mole of carbon dioxide.
$\text{Number of moles of O present in}0.25\text{moles of carbon dioxide}=2\times 0.25=0.5\text{mol}$
Mass of $O$ atom = $(0.5\times 16)\text{g}=8\text{g}$