One mole of an ideal gas occupies a volume of ______ litre at 273 K and 1 atm pressure.

Explanation

Using PV=nRT with n=1 mol, T=273 K, P=1 atm and R≈0.082057 L·atm·mol⁻¹·K⁻¹ gives V≈22.4 L. The stated pressure matters: using 1 bar instead of 1 atm gives a different molar volume. Thus 22.4 litres is the appropriate rounded choice here.