Which of the following statement about the catalyst is/are true?

Options

A. A catalyst makes the reaction feasible by making `Delta G` more negative.
B. A catalyst makes equilibrium constant more favourable for forward reaction
C. A catalyst accelerate rate of reaction by bringing down the activation energy
D. A catalyst always increases the rate of reaction.

Answer

To determine which statements about catalysts are true, let's analyze each option step by step.

### Step 1: Understanding the Definition of a Catalyst
A catalyst is a substance that alters the rate of a chemical reaction by providing an alternative pathway with a lower activation energy. It does not get consumed in the reaction and can accelerate both the forward and reverse reactions.

### Step 2: Analyzing Each Statement

**Option 1: "Catalyst makes the reaction feasible by making delta G more negative."**
- This statement is **false**. A catalyst does not change the Gibbs free energy (ΔG) of a reaction. It only affects the rate at which equilibrium is reached but does not make the reaction more thermodynamically favorable.

**Option 2: "Catalyst makes equilibrium constant more favorable for forward reaction."**
- This statement is also **false**. A catalyst does not change the equilibrium constant; it affects both the forward and backward reactions equally, thus not favoring one over the other.

**Option 3: "A catalyst accelerates the rate of the reaction by bringing down the activation energy."**
- This statement is **true**. A catalyst lowers the activation energy barrier, which increases the rate of the reaction.

**Option 4: "A catalyst always increases the rate of the reaction."**
- This statement is **false**. While catalysts generally increase the rate of a reaction, there are conditions under which a catalyst may not have any effect or could even slow down the reaction.

### Conclusion
From the analysis, the only true statement about catalysts is **Option 3**.

### Summary of True Statements
- Only **Option 3** is true: "A catalyst accelerates the rate of the reaction by bringing down the activation energy."

---