**Which of the following reactions have a positive ?Srxn? Check all that apply.**

**2A(g) + B(s) --> 3C(g) 2A(g) + B(g) --> C(g) A(g) + B(g) -->C(g) 2A(g) + 2B(g) -->5C(g)**

**Concepts and reason**

**Entropy:**

The entropy **S** describes the randomness and disorders of molecules, depending on the number of various arrangements possible for the molecules, in a given system of reaction.

**Fundamentals**

As the randomness of the molecules increases, the entropy also increases and gives a positive sign.

Conditions for to be positive:

- Entropy increases as the phase changes from solid to liquid, liquid to gas or solid to gas.
- If the change in number of moles is positive, then the entropy is also positive.

**Answer:**

The given reaction is as follows:

**Explanation:**

The change in number of moles is positive. Hence, the randomness of the molecules increases, which results in giving positive entropy.

The given reaction is as follows:

The change in number of moles is negative. Hence, the randomness of the molecules decreases, which results in giving negative entropy.

The given reaction is as follows:

**Explanation:**

The change in number of moles is negative. Hence, the randomness of the molecules decreases, which results in giving negative entropy.

The given reaction is as follows:

The change in number of moles is positive. Hence, the randomness of the molecules increases, which results in giving positive entropy.