# How many molecules does 1 mole of O_2 gas have?

In $1$ $m o l$ ${O}_{2}$ gas, by definition you have Avogadro's number of MOLECULES.
Avogadro's number, ${N}_{A}$ $=$ $6.022140857 \times {10}^{23}$. In the given quantity of dioxygen gas there are $2 \times {N}_{A}$ oxygen atoms.