NEET levelSingle correct optionDifficulty 1 of 3rg166
The compressibility factor of a gas is found to be exactly 1 at a particular pressure and temperature. Which conclusion is correct?
AThe gas is ideal under all conditions
BThe attractive and repulsive deviations cancel at this state, or the gas is at very low pressure
CThe gas has no intermolecular forces
DThe gas is at its critical point
Answer: B
Z=1 at one state does not prove ideality everywhere. A real gas gives Z=1 when P→0, or at the pressure where the attraction and excluded volume corrections happen to cancel. At other pressures the same gas deviates.