Q.Explain whether a gas approaches ideal behavior or deviates from ideal behaviour if

The compressibility factor, $Z = \dfrac{pV}{nRT}$, is a dimensionless number measuring how far a real gas's behaviour departs from ideal-gas behaviour under given conditions.

• $Z = 1$ throughout for a perfectly ideal gas
• $Z < 1$ means the gas is more compressible than ideal — attractive forces pull molecules closer than the ideal equation predicts …