One mole of a monoatomic real gas satisfies the equation p(V-b) = RT where b is a constant. The relationship of interatomic potential V(r) and interatomic distance r for the gas is given by
(A)(see structure)
(B)(see structure)
(C)(see structure)✓ Correct
(D)(see structure)
Answer: (C)
Solution
The equation p(V-b) = RT represents a real gas with excluded volume (b > 0) but no intermolecular attractive forces. This is similar to a hard-sphere model.
The potential energy diagram for such a gas shows:
V(r) = ∞ for r < r₀ (hard-sphere repulsion at close distances)
V(r) = 0 for r ≥ r₀ (no attractive forces at larger distances)
This corresponds to a step function with infinite repulsion at contact and zero interaction beyond. The correct graph is option (C).
JEE Advanced · 2015 · 24 May 2015 · Paper 2 · One or more correct options
