What volume is occupied by $100.0$ grams of oxygen gas $\left(O_2\right)$ at STP?

The correct option is D $70L$

$numberofmoles=\frac{weight}{molecularweight}$

$100.0g{O}_2$ at STP $=\frac{100}{32}=3.125moles$

$1mole$ gas at STP occupies volume$=22.4L$

$3.125moles=22.4\times 3.125=70L$