If $1 \ g$ of each of the following gases are taken at $STP$,which of the gases will occupy $(a)$ greatest volume and $(b)$ smallest volume? $CO, H_2O, CH_4, NO$

(N/A) From Avogadro's law,the volume of $1 \ mol$ of any gas at $STP$ is $22.4 \ L$.
The volume occupied by $1 \ g$ of a gas is given by $\frac{22.4 \ L}{\text{Molar mass in } g \ mol^{-1}}$.
$1$. For $CO$ (Molar mass $= 28 \ g \ mol^{-1}$): Volume $= \frac{22.4}{28} = 0.80 \ L$.
$2$. For $H_2O$ (Molar mass $= 18 \ g \ mol^{-1}$): Volume $= \frac{22.4}{18} \approx 1.24 \ L$.
$3$. For $CH_4$ (Molar mass $= 16 \ g \ mol^{-1}$): Volume $= \frac{22.4}{16} = 1.40 \ L$.
$4$. For $NO$ (Molar mass $= 30 \ g \ mol^{-1}$): Volume $= \frac{22.4}{30} \approx 0.75 \ L$.
Comparing the volumes,$CH_4$ occupies the greatest volume $(1.40 \ L)$ and $NO$ occupies the smallest volume $(0.75 \ L)$.