Graham's Law of Diffusion Steps:

• Apply Graham's law: diffusion rate is inversely proportional to the square root of molar mass.
• Calculate molar mass of nitrogen (N₂): 28 g/mol.
• Compute molar masses: NH₃ (17 g/mol), CO (28 g/mol), C₂H₆ (30 g/mol), O₂ (32 g/mol).
• Compare rates: gas with equal molar mass to N₂ diffuses at the same rate.

Why B is correct:

• CO has the same molar mass (28 g/mol) as N₂, so their diffusion rates are equal per Graham's law (rate ∝ 1/√M).

Why the others are wrong:

• A: NH₃ is lighter (17 g/mol), so it diffuses faster.
• C: C₂H₆ is heavier (30 g/mol), so it diffuses slower.
• D: O₂ is heavier (32 g/mol), so it diffuses slower.

Final answer: B