In the manufacture of metallic sodium by the fused salt electrolysis `(` Down's process ) a small amount of `CaCl_(2)` is added to `:`

Options

A. Imrove the electrical conduction
B. Decrease the melting temperature
C. Stabilising the metallic sodium
D. Increase the temperature of electrolysis

Explanation

To solve the question regarding the addition of calcium chloride (CaCl₂) in the manufacture of metallic sodium by the fused salt electrolysis (Down's process), we can follow these steps:

### Step 1: Understand the Down's Process
The Down's process is an electrolytic method used to produce metallic sodium from sodium chloride (NaCl). In this process, NaCl is melted, and then electrolysis is performed to separate sodium (Na) and chlorine (Cl).

### Step 2: Recognize the Problem with High Temperature
During the electrolysis of NaCl, the reaction generates a significant amount of heat, which can lead to very high temperatures. This high temperature can be problematic as it can cause equipment damage and affect the efficiency of the electrolysis process.

### Step 3: Identify the Role of Calcium Chloride
To mitigate the issue of high temperatures, a small amount of calcium chloride (CaCl₂) is added to the molten NaCl. The addition of CaCl₂ serves to lower the melting point of the salt mixture.

### Step 4: Conclude the Effect of Adding CaCl₂
By lowering the melting temperature of the system, CaCl₂ helps to maintain a more stable and manageable temperature during the electrolysis process. This allows for more efficient production of sodium without the risks associated with excessively high temperatures.

### Final Answer
The correct reason for adding a small amount of CaCl₂ in the Down's process is to **decrease the melting temperature of the system**.

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