When washing soda is heated below 373 K, it forms:-

Options

A. `Na_(2)CO_(3)`
B. `Na_(2)CO_(3).H_(2)O`
C. Both (A) & (B) (D)
D. `Na_(2)CO_(3). 5H_(2)O`

Explanation

To solve the question regarding the heating of washing soda (sodium carbonate decahydrate) below 373 K, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Chemical Formula of Washing Soda**:
- Washing soda is chemically known as sodium carbonate decahydrate, which has the formula:
\[ \text{Na}_2\text{CO}_3 \cdot 10\text{H}_2\text{O} \]

2. **Understand the Heating Process**:
- When washing soda is heated, it undergoes a process of dehydration. This means it will lose some of its water of crystallization.

3. **Determine the Temperature Range**:
- The question specifies that the heating occurs below 373 K. This is an important detail because the behavior of the compound changes with temperature.

4. **Identify the Products of Heating Below 373 K**:
- Below 373 K, washing soda loses 9 molecules of water:
\[ \text{Na}_2\text{CO}_3 \cdot 10\text{H}_2\text{O} \rightarrow \text{Na}_2\text{CO}_3 \cdot \text{H}_2\text{O} + 9\text{H}_2\text{O} \]
- The product formed is sodium carbonate monohydrate:
\[ \text{Na}_2\text{CO}_3 \cdot \text{H}_2\text{O} \]

5. **Conclusion**:
- Therefore, when washing soda is heated below 373 K, it forms sodium carbonate monohydrate, represented as:
\[ \text{Na}_2\text{CO}_3 \cdot \text{H}_2\text{O} \]

### Final Answer:
When washing soda is heated below 373 K, it forms sodium carbonate monohydrate (\(\text{Na}_2\text{CO}_3 \cdot \text{H}_2\text{O}\)).

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