Answer:
Cl2, N2O, F2, H2S
Explanation:
You must recall Graham's law at this point. Graham's law states that the rate of diffusion of a gas is inversely proportional to the square root of its vapour density or molar mass.
Now, the greater the molar mass of a gas, the lesser the rate of diffusion of that gas. The gas that will diffuse more slowly than oxygen must have a higher molar mass than oxygen. Oxygen has a molar mass of 32gmol-1, let us look at the molar masses of other gases.
F2= 37.99681 g/mol
Ne= 20.1797 gmol-1
N2O= 44.013 g/mol
C2H2= 26.04 g/mol
NO= 30.01 g/mol
Cl2= 70.906 gmol-1
H2S= 34.1 g/mol
Hence in order of decreasing slower diffusion than oxygen gas
Cl2, N2O, F2, H2S
