There is a lot of metric calculations, According to the rules of Avogadro,
22.41 litres of any ideal gast at STP contains 6.023 X 20^23 molecules and it is equal to 1mol of the gas.
Therefore the answer would be 22.41 litres of the ideal gas at STP contains 6.023 X 10^23 molecules.
I hope this helps you :)
