JEE Main · 2023 · 06 Apr 2023 · Shift 1 · Chemical Thermodynamics

On a plot of Gibbs energy against extent of reaction, the sign of the slope $\mathrm{d}G/\mathrm{d}\xi$ decides the behaviour: a negative slope means the reaction is spontaneous, a zero slope at the minimum means equilibrium, and a positive slope means it is non-spontaneous. Point (a) lies on the descending branch, so the reaction is spontaneous there; point (b) sits at the minimum, so the system is at equilibrium; point (c) lies on the rising branch, so the reaction is non-spontaneous. Testing the statements, the claim that the system is at equilibrium at (b) and non-spontaneous at (c) holds, and the claim that it is spontaneous at (a) and non-spontaneous at (c) holds, while the other two fail. The number of true statements is 2.