# What volume is expressed by a mass of 0.50*g of oxygen gas at "STP"?

Well, the $\text{molar volume at STP}$ is $22.4 \cdot L \cdot m o {l}^{-} 1$. I make it approx. $400 \cdot m L$.
"Volume"=(0.50*cancelg)/(32.00*cancelg*cancel(mol^-1))xx22.4*L*cancel(mol^-1)=??*L