The starting material used in Solvay's process are

Options

A. Sodium sulphate
B. Brine solution
C. Carnallite
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding Solvay's Process:**
- The Solvay process is a method for producing sodium carbonate (soda ash) from sodium chloride (common salt) and other materials.

2. **Identifying the Starting Material:**
- The primary starting material used in the Solvay process is a concentrated solution of sodium chloride, commonly referred to as brine. This brine solution is typically around 28% concentration.

3. **Chemical Reactions Involved:**
- The process begins with the reaction of sodium chloride (NaCl) with ammonium bicarbonate (NH4HCO3). The reaction can be summarized as:
\[ \text{NaCl} + \text{NH}_4\text{HCO}_3 \rightarrow \text{NaHCO}_3 + \text{NH}_4\text{Cl} \]
- This reaction produces sodium bicarbonate (NaHCO3) and ammonium chloride (NH4Cl).

4. **Further Processing:**
- Upon heating sodium bicarbonate, it decomposes to form sodium carbonate, carbon dioxide, and water:
\[ \text{2 NaHCO}_3 \xrightarrow{\text{heat}} \text{Na}_2\text{CO}_3 + \text{CO}_2 + \text{H}_2\text{O} \]

5. **Conclusion:**
- Therefore, the starting material used in the Solvay process is the concentrated sodium chloride solution (brine).

**Final Answer:**
The starting material used in Solvay's process is concentrated sodium chloride solution (brine).

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