WBJEE 2024 Physics & Chemistry Paper

To determine the incorrect statement for a spontaneous process, let's review some basic thermodynamic principles associated with spontaneity and Gibbs free energy (G), entropy (S), and internal energy (U).
For a process to be spontaneous, certain conditions need to be met:
The change in Gibbs free energy at constant temperature (T) and pressure (P), ∆G‌system, ‌ must be negative:
(∆G‌system ‌‌‌)T,P<0
The total entropy change, which is the sum of the entropy change in the system and the entropy change in the surroundings, must be positive:
(∆S‌system ‌)+(∆S‌surroundings ‌)>0
With these in mind, let's assess the given options:
Option A:
This states:
(∆G‌system ‌)T,P>0
This is incorrect for a spontaneous process since, as mentioned, the Gibbs free energy change should be negative for spontaneity.
Option B:
This states:
(∆S‌system ‌)+(∆S‌surroundings ‌‌‌)>0
This is correct because the overall entropy change for a spontaneous process must be positive.
Option C:
This states:
(∆G‌system ‌)T,P<0
This is correct, as ∆G should be negative for a spontaneous process.
Option D:
This states:
(∆U‌system ‌)S,v<0
This describes the change in internal energy at constant entropy (S) and volume (v). This is not directly related to the criteria for spontaneity, making it neither correct nor incorrect within this context. However, it's not a standard criterion for determining spontaneity.
The incorrect statement regarding spontaneity is clearly:
Option A:
(∆G‌system ‌‌‌)T,P>0