The behaviour of a real gas is usually depicted by plotting compressibility factor versus at a const — States of Matter and Gaseous State Chemistry Question

💡 Solution & Explanation

At high temperatures and pressures, the thermal energy minimizes the effect of the attractive term ($a/V^2$) making it negligible compared to the very high external pressure $P$. However, the molecules are forced closely together, meaning the excluded volume ($b$) cannot be ignored. The equation simplifies to $P(V-b)=RT \implies Z = 1 + Pb/RT > 1$. Therefore, correct answer is A.