AbOVE 373K, the monohydrate sodium carbonate becomes completely anhydrous and called as

Options

A. potash ash
B. soda ash
C. pearl ash
D. brine ash

Answer

To solve the question, we need to identify what monohydrate sodium carbonate becomes when heated above 373 K and what it is commonly referred to as.

### Step-by-Step Solution:

1. **Understand the Substance**:
- The substance in question is monohydrate sodium carbonate, which has the chemical formula Na2CO3·H2O.

2. **Heating the Substance**:
- When monohydrate sodium carbonate is heated above 373 K, it loses its water of hydration. This process converts it into an anhydrous form.

3. **Identify the Anhydrous Form**:
- The anhydrous form of sodium carbonate is simply Na2CO3, which is a white powder.

4. **Common Name**:
- The anhydrous sodium carbonate (Na2CO3) is commonly known as "soda ash."

5. **Evaluate the Options**:
- Now, we need to evaluate the options provided in the question:
- Option 1: Potash ash - Incorrect
- Option 2: Soda ash - Correct
- Option 3: Pearl ash - Incorrect
- Option 4: Brine ash - Incorrect

6. **Conclusion**:
- Therefore, the correct answer to the question is that above 373 K, monohydrate sodium carbonate becomes completely anhydrous and is called "soda ash."

### Final Answer:
The monohydrate sodium carbonate becomes completely anhydrous above 373 K and is called **soda ash**.

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