At STP, how many moles are in 21.5 L CH4?

0.96 mole of CH4.

Explanation:

From a background knowledge of gas laws, we understood that 1 mole of a gas occupy 22.4 L at STP. This implies that 1 mole of CH4 also occupy 22.4 L at STP.

Now, we shall determine the number of mole of CH4 that will occupy 21.5 L at STP. This is illustrated below:

1 mole of CH4 occupied 22.4 L at STP.

Therefore, Xmol of CH4 will occupy 21.5 L at STP. i.e

Xmol of CH4 = (1 × 21.5)/22.4

Xmol of CH4 = 0.96 mole

Therefore, 0.96 mole of CH4 will occupy 21.5 L at STP.

i believe the answer is three water molecules