Match column (I) (process) with column (II) (electrolyte)
`{:("Column (I) (process)", "Column (II) (electrolyte)"),( (1) "Castner Kellner.s cell", (P) Cu),( (2) "Self-reduction", (Q) "fused " (Al_(2)O_(3)+Na_(3)AlF_(6)+CaF_(2))),( (3) "Hall-Heroult", (R ) "Brine solution"):}`

Answer

To solve the problem of matching the processes from Column (I) with the corresponding electrolytes from Column (II), we will analyze each process step by step.

### Step-by-Step Solution:

1. **Identify the first process: Castner-Kellner Cell**
- The Castner-Kellner cell is an electrolytic cell used for the production of sodium hydroxide (NaOH) from brine solution (concentrated sodium chloride solution).
- **Match:** Therefore, Castner-Kellner cell matches with **(R) Brine solution**.

2. **Identify the second process: Self-reduction**
- Self-reduction refers to a process where less electropositive metals, such as lead, copper, and mercury, undergo reduction without the need for an external reducing agent.
- For example, copper oxide (CuO) can react with copper sulfide (Cu2S) to yield copper (Cu) and sulfur dioxide (SO2).
- **Match:** Hence, self-reduction matches with **(P) Cu** (copper).

3. **Identify the third process: Hall-Heroult Process**
- The Hall-Heroult process is an industrial method for smelting aluminum. It involves the electrolysis of aluminum oxide (Al2O3) dissolved in cryolite (Na3AlF6) and other additives.
- **Match:** Thus, the Hall-Heroult process matches with **(Q) "fused" (Al2O3 + Na3AlF6 + CaF2)**.

### Final Matches:
- (1) Castner-Kellner Cell → (R) Brine solution
- (2) Self-reduction → (P) Cu
- (3) Hall-Heroult Process → (Q) "fused" (Al2O3 + Na3AlF6 + CaF2)

### Summary of Matches:
1. **1 → R**
2. **2 → P**
3. **3 → Q**