Where are the more molecules: in a glass of water or in the air inside an “empty” barrel?

Where are the more molecules: in a glass of water or in the air inside an “empty” barrel? The volume of the glass is 200 cm3, the volume of the barrel is 0.4 m3, the air is under normal conditions.

For a correct, clear and understandable answer to this question, we will have to find out how much mole is contained in 1 and 2 cases.

The fact is that it is from the number of moles in a substance that we can understand which of them has more molecules.

So let’s start counting.

In a glass, the number of moles = 200/18 ≈ 11 moles.

The number of moles in the barrel will be = 400 / 22.4 ≈ 18 moles.

And since 18 moles are more than 11 moles, we can say that there are more molecules in the barrel. Since 1 mole always contains the same number of molecules.