Which reagent is used in catalytic amount in an esterification reaction ?
I. Aq. NaOH
II Conc, `H_2SO_4`

Options

A. Both I and II
B. Neither I nor II
C. Only I
D. Only II

Answer

To determine which reagent is used in catalytic amounts in an esterification reaction, we need to analyze the two options provided:

1. **Aq. NaOH**: This is an aqueous solution of sodium hydroxide, which is a strong base. In the context of esterification, it does not serve as a catalyst. Instead, it would lead to a different reaction known as saponification, where esters are hydrolyzed to form alcohols and carboxylate salts.

2. **Conc. H₂SO₄**: Concentrated sulfuric acid is commonly used as a catalyst in esterification reactions. It provides the acidic medium necessary for the reaction to proceed, facilitating the formation of the ester from a carboxylic acid and an alcohol. It is used in catalytic amounts, meaning only a small quantity is needed to increase the rate of the reaction without being consumed in the process.

### Step-by-step Solution:
1. **Identify the reaction type**: Recognize that esterification is the reaction between a carboxylic acid and an alcohol to form an ester and water.

2. **Evaluate the reagents**:
- **Aq. NaOH**: This is a strong base and not suitable for esterification as it would lead to hydrolysis instead.
- **Conc. H₂SO₄**: This is an acid that can catalyze the esterification reaction by providing the necessary acidic environment.

3. **Determine the correct reagent**: Since concentrated sulfuric acid (Conc. H₂SO₄) is used in catalytic amounts to facilitate the reaction, it is the correct answer.

4. **Conclusion**: The correct reagent used in catalytic amounts in an esterification reaction is **Conc. H₂SO₄**.

### Final Answer:
**II. Conc. H₂SO₄** is the reagent used in catalytic amount in an esterification reaction.

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