# How many atoms of helium gas are in 22.4 L at STP?

$\text{There is a ONE MOLE quantity of helium atoms.....}$
A volume of $22.4 \cdot L$ gas under standard conditions of temperature and pressure $\left(1 \cdot a t m , 273.15 \cdot K\right)$ specifies a MOLAR quantity of gas. That is there are $6.022 \times {10}^{23}$ individual helium atoms. How many individual atoms if we changed the identity of the gas to dinitrogen or dioxygen?