In the preparation of soap, which is used?

Options

A. NaOH
B. Na
C. Sodium silicate
D. `CH_3 COONa`

Explanation

To answer the question "In the preparation of soap, which is used?", we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding the Ingredients**:
In the preparation of soap, we need to identify the key ingredients typically used. The options provided are NaOH (sodium hydroxide), sodium silicate, and CH3COONa (sodium acetate).

2. **Identifying the Correct Ingredient**:
The primary ingredient used in the soap-making process is NaOH (sodium hydroxide). This is because NaOH is a strong base that reacts with fats or oils.

3. **The Saponification Process**:
The process of making soap is called saponification. When fats (which are esters of glycerol and fatty acids) are heated with NaOH, they undergo hydrolysis. This reaction produces soap (the salt of fatty acids) and glycerol.

4. **Chemical Reaction**:
The general reaction can be represented as:
\[ \text{Fat} + \text{NaOH} \rightarrow \text{Soap} + \text{Glycerol} \]
Here, the fat reacts with sodium hydroxide to produce soap and glycerol.

5. **Conclusion**:
Therefore, the correct answer to the question is that NaOH is used in the preparation of soap. Other options like sodium silicate and CH3COONa do not contribute to the soap-making process effectively.

### Final Answer:
The correct answer is **NaOH (sodium hydroxide)**.

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