Basic gas law reference: The molar volume occupied by one gm·mol (one mole) of an ideal gas at standard temperature and pressure (S.T.P.) is approximately equal to which of the following?

Introduction / Context:
The molar volume at S.T.P. is a benchmark figure for gas calculations, quick estimates of moles from volumes, and stoichiometry in reaction engineering. Though different standards exist (e.g., IUPAC’s 0°C, 1 bar), many textbooks still reference 22.414 L/mol at 0°C and 1 atm.

Given Data / Assumptions:

• Ideal-gas behaviour assumed.
• Classical S.T.P. convention: 0°C (273.15 K) and 1 atm.

Concept / Approach:
Using PV = nRT with n = 1 mol, P = 1 atm, T = 273.15 K, and R = 0.082057 L·atm·mol^-1·K^-1 gives V ≈ 22.414 L. This is typically rounded to 22.4 L for quick work.

Step-by-Step Solution:

Verification / Alternative check:
If using 1 bar instead of 1 atm, the molar volume is ~22.71 L/mol. The answer here follows the 1 atm convention consistent with many problem sets.

Why Other Options Are Wrong:

• 22400 litres: Off by a factor of 1000 (confuses litres with millilitres).
• 22.4 c.c.: Off by 1000 (1 L = 1000 c.c.).
• 359 litres: Approximates 12.7 moles at STP, not one mole.

Common Pitfalls:
Mixing definitions of S.T.P. or mixing units (L, mL, c.c.). Always check the stated standard before using the molar volume constant.

Final Answer:
22.4 litres