Chemistry - Thermodynamics - II Question with Solution | TestHub

Question Explanation : Find incorrect option regarding entropy

Concept : Second law of thermodynamics

Solution :

Option (1) (Correct): Entropy is a state function, but its thermodynamic definition is based on a reversible exchange of heat: $\mathrm{dS}=\frac{{\mathrm{dQ}}_{\text{rev }}}{\mathrm{T}}$.

To calculate the change in entropy between two states, you must devise a reversible path between them, regardless of whether the actual process was reversible or irreversible.- Option 2 (Correct): Entropy (S) is indeed a state function. This means its value depends only on the current state of the system (like its temperature and pressure) and not on the path taken to reach that state.-

Option 3 (Correct): In a perfectly reversible process, the increase in entropy of one part of the universe is exactly balanced by the decrease in entropy of another part. Thus, the total entropy of the universe $\left(\Delta {\mathrm{S}}_{\text{univ }}=\Delta {\mathrm{S}}_{\text{sys }}+\Delta {\mathrm{S}}_{\text{surr }}\right)$ remains constant (zero change).-

Option 4 (Incorrect): The Second Law of Thermodynamics states that the entropy of an isolated system (like the universe) tends to increase over time. Unlike energy, entropy is not conserved; it is created during every spontaneous or irreversible process. Therefore, the law is based on the increase of entropy, not its conservation.

Final answer : Option (D)

Second law of thermodynamics is based on conservation of entropy of universe.