The heat of neutralisation will be highest in

Options

A. `HCI + NaOH`
B. `NH_(4)OH + H_(2)SO_(4)`
C. `CH_(3)COOH + NaOH`
D. `CH_(3)COOH + NH_(4)OH`

Explanation

To determine which combination of acid and base yields the highest heat of neutralization, we need to understand the concept of heat of neutralization and how it varies with the strength of acids and bases involved in the reaction.

### Step-by-Step Solution:

1. **Definition of Heat of Neutralization**:
- The heat of neutralization is defined as the amount of heat released when an acid reacts with a base to form salt and water. This process is exothermic, meaning it releases heat.

2. **Identify the Types of Acids and Bases**:
- Acids can be classified as strong or weak. Strong acids completely dissociate in water, releasing H⁺ ions, while weak acids partially dissociate.
- Similarly, bases can also be classified as strong or weak. Strong bases completely dissociate in water, releasing OH⁻ ions, while weak bases do not fully dissociate.

3. **Understanding the Reaction**:
- In a neutralization reaction, the H⁺ ions from the acid combine with the OH⁻ ions from the base to form water (H₂O). The reaction can be represented as:
\[ \text{HA} + \text{BOH} \rightarrow \text{BA} + \text{H}_2\text{O} \]
- Here, HA represents the acid, and BOH represents the base.

4. **Effect of Strength on Heat of Neutralization**:
- The heat of neutralization is highest when both the acid and the base are strong. This is because strong acids and strong bases dissociate completely, leading to a greater release of H⁺ and OH⁻ ions, which results in more water formation and thus more heat release.
- Conversely, if either the acid or the base is weak, the reaction does not go to completion, resulting in less heat being released.

5. **Conclusion**:
- Therefore, the heat of neutralization will be highest in the case of a reaction between a strong acid and a strong base.

### Final Answer:
The heat of neutralization will be highest in the case of a strong acid reacting with a strong base.