Which pair of molecules is expected to have the most different properties?

This question is incomplete

The completed question is below

Which pair of molecules is expected to have the most different properties?

CO and NO

SO₂ and CH₄

The correct answer is SO₂ and CH₄

Explanation:

All the four substances are gases at room temperature.

Carbon monoxide (CO) and nitric oxide (NO) are both reactive oxides. They are both polar and inorganic also, hence should have some similar properties (based on there origin/composition and polarity).

Sulphur dioxide (SO₂) is polar because it's a bent molecule, methane (CH₄) is non-polar because of the tetrahedral shape of it's molecule. Methane is an organic molecule while sulphur dioxide is an inorganic molecule.

From the above, it can be deduced that SO₂ and CH₄ are expected to have different properties. For example, the polarity of SO₂ makes it dissolve in water to form an acidic solution while methane does not dissolve in water and hence doesn't form an acidic solution.