Sodium carbonate is manufactured by Solvay process. The products that are recycled are

Options

A. `CO_2and NH_3`
B. `CO_2 and NH_4Cl`
C. `NaCl, CaO`
D. `CaCl_2, CO`.

Explanation

To solve the question regarding the products that are recycled in the Solvay process for the manufacture of sodium carbonate, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Solvay Process**: The Solvay process is a method used to produce sodium carbonate (soda ash) from sodium chloride (NaCl) and limestone (calcium carbonate, CaCO3).

2. **Initial Reactions**: The process begins with the reaction of ammonia (NH3) with carbon dioxide (CO2) and water (H2O) to form ammonium carbonate ((NH4)2CO3).

\[ \text{NH}_3 + \text{CO}_2 + \text{H}_2\text{O} \rightarrow (NH_4)_2CO_3 \]

3. **Formation of Ammonium Bicarbonate**: The ammonium carbonate reacts with additional carbon dioxide and water to form ammonium bicarbonate (NH4HCO3).

\[ (NH_4)_2CO_3 + \text{CO}_2 + \text{H}_2\text{O} \rightarrow 2 \text{NH}_4\text{HCO}_3 \]

4. **Reaction with Brine**: The saturated solution of ammonium bicarbonate then reacts with brine (aqueous NaCl) to produce ammonium chloride (NH4Cl) and sodium bicarbonate (NaHCO3).

\[ \text{NH}_4\text{HCO}_3 + \text{NaCl} \rightarrow \text{NH}_4\text{Cl} + \text{NaHCO}_3 \]

5. **Calcination of Sodium Bicarbonate**: The sodium bicarbonate is then heated (calcined) to produce sodium carbonate (Na2CO3), releasing carbon dioxide and water.

\[ 2 \text{NaHCO}_3 \rightarrow \text{Na}_2\text{CO}_3 + \text{CO}_2 + \text{H}_2\text{O} \]

6. **Recycling Products**: The key point in the Solvay process is that ammonia and carbon dioxide are recycled. After the reaction of ammonium bicarbonate, heating it regenerates ammonia and carbon dioxide, which can be reused in the process.

### Conclusion:
The products that are recycled in the Solvay process for the manufacture of sodium carbonate are **ammonia (NH3)** and **carbon dioxide (CO2)**.

### Final Answer:
**A) Carbon dioxide and ammonia**