The role of fluorspar during the electrolysis of molten alumina is
(i) To reduce the melting point
(ii) To increase conductivity
(iii) As a seeding agent

Options

A. All are correct
B. Only (i) is correct
C. (i), (ii) are correct
D. (i), (iii) are correct

Answer

To determine the role of fluorspar (calcium fluoride, CaF2) during the electrolysis of molten alumina, we can analyze the functions it serves in the process. Here’s a step-by-step breakdown of the solution:

### Step 1: Understanding the Components
Fluorspar is calcium fluoride (CaF2) and is often added to molten alumina (Al2O3) during the electrolysis process. The primary purpose of adding fluorspar is to enhance the efficiency of the electrolysis.

**Hint:** Identify the chemical composition of fluorspar and its common uses in metallurgy.

### Step 2: Analyzing the Melting Point
Molten alumina has a very high melting point, which makes the electrolysis process energy-intensive. One of the roles of fluorspar is to reduce this melting point, making it easier to maintain the molten state during electrolysis.

**Hint:** Consider how the addition of a substance can affect the melting point of a compound.

### Step 3: Evaluating Conductivity
In addition to reducing the melting point, fluorspar also increases the conductivity of the molten alumina mixture. Higher conductivity is essential for efficient electrolysis as it allows for better ion movement and current flow.

**Hint:** Think about why conductivity is important in electrolysis and how it can be improved.

### Step 4: Considering the Seeding Agent Role
The third option suggests that fluorspar acts as a seeding agent. However, this is not a primary role of fluorspar in the electrolysis of alumina. Seeding agents typically help in the crystallization process, which is not relevant in this context.

**Hint:** Reflect on the definition of a seeding agent and its typical applications in chemistry.

### Step 5: Conclusion
Based on the analysis:
- Fluorspar reduces the melting point of alumina (i).
- Fluorspar increases the conductivity of the molten mixture (ii).
- Fluorspar does not function as a seeding agent (iii).

Thus, the correct answer is that fluorspar serves to reduce the melting point and increase conductivity, but not as a seeding agent.

**Final Answer:** (i) To reduce the melting point and (ii) To increase conductivity are correct; (iii) As a seeding agent is incorrect.