Select the pair of oxidation processes,
(a) `2Cu^(2+) rarr Cu_(2)^(2+)`
( b) `MnO_(4)^(-) rarr Mn^(2+)`
( c ) `[Fe(CN)_(6) ]^(-4) rarr [ Fe(CN)_(6)]^(-3)`
( d) `2I^(-) rarr I_(2)`

Options

A. a,b
B. c,d
C. a,d
D. b,c

Answer

To determine the pair of oxidation processes from the given options, we need to analyze each reaction and identify whether oxidation (loss of electrons or increase in oxidation state) is occurring.

### Step-by-Step Solution:

1. **Analyze Option (a): `2Cu^(2+) → Cu_(2)^(2+)`**
- The oxidation state of Cu in `Cu^(2+)` is +2.
- In `Cu_(2)^(2+)`, the overall charge is +2, which indicates that the oxidation state of Cu is effectively +1 (since there are two Cu atoms).
- Since the oxidation state decreases from +2 to +1, this is a reduction process, not oxidation.

**Conclusion**: This is not an oxidation process.

2. **Analyze Option (b): `MnO_(4)^(-) → Mn^(2+)`**
- In `MnO_(4)^(-)`, the oxidation state of Mn can be calculated as follows:
- Let the oxidation state of Mn be x.
- The total charge from 4 oxygen atoms is -8 (4 * -2).
- The overall charge of the ion is -1, so:
\[ x - 8 = -1 \implies x = +7 \]
- In `Mn^(2+)`, the oxidation state of Mn is +2.
- The oxidation state decreases from +7 to +2, indicating a reduction process.

**Conclusion**: This is not an oxidation process.

3. **Analyze Option (c): `[Fe(CN)_(6)]^(-4) → [Fe(CN)_(6)]^(-3)`**
- In `[Fe(CN)_(6)]^(-4)`, the overall charge is -4.
- The charge of 6 cyanide ions (CN^-) is -6, so:
- Let the oxidation state of Fe be x:
\[ x - 6 = -4 \implies x = +2 \]
- In `[Fe(CN)_(6)]^(-3)`, the overall charge is -3.
- The charge of 6 cyanide ions remains -6, so:
- The oxidation state of Fe is:
\[ x - 6 = -3 \implies x = +3 \]
- The oxidation state increases from +2 to +3, indicating an oxidation process.

**Conclusion**: This is an oxidation process.

4. **Analyze Option (d): `2I^(-) → I_(2)`**
- The oxidation state of I in `I^(-)` is -1.
- In molecular iodine `I_(2)`, the oxidation state of I is 0.
- The oxidation state increases from -1 to 0, indicating an oxidation process.

**Conclusion**: This is an oxidation process.

### Final Conclusion:
The pairs of oxidation processes are found in options (c) and (d). Therefore, the correct answer is:

**Correct Options**: (c) and (d)