Assertion (A): Decrease in free energy causes spontaneous reaction
Reason (R ) : Spontaneous reactions are invariably exothermic.

Options

A. If both (A) and (R ) are correct, and (R ) is the correct explanation for (A).
B. If the both (A) and (R ) are correct, but(R ) is not a correct explanation for (A).
C. If (A) is correct, but (R ) is incorrect.
D. If (A) is incorrect, but (R ) is correct.

Explanation

To solve the question regarding the assertion and reason provided, we will analyze both statements step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that a decrease in free energy causes a spontaneous reaction.
- In thermodynamics, a reaction is considered spontaneous if it can occur without external intervention. This is determined by the change in Gibbs free energy (ΔG).
- The relationship is given by the equation:
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