we can use the ideal gas law equation to find the volume occupied by O₂
PV = nRT
where P - pressure - 1.3 atm x 101 325 Pa/atm = 131 723 Pa
V - volume
n - number of moles - 2 mol
R - universal gas constant - 8.314 Jmol⁻¹K⁻¹
T - temperature - 300 K
Substituting these values in the equation
131 723 Pa x V = 2 mol x 8.314 Jmol⁻¹K⁻¹ x 300 K
V = 37.9 L
volume occupied is 37.9 L