Match List-I (complex ions) with List-II (number of unpaired electrons) and select the correct answers using the codes given below lists:
`{:(List-I,,,,List-II),((Compl ex ion),,,,(Number of Unpaired El ectrons )),(A.,[CrF_6]^(4-),,1.,On e),(B.,[MnF_6]^(4-),,2.,Two),(C.,[Cr(CN)_6]^(4-),,3.,Three),(D.,[Mn(CN)_6]^(4-),,4.,Four), (,,,5.,Five):}`

Options

A. (a) `{:(A,B,C,D,),(4,1,2,5,):}`
B. (b) `{:(A,B,C,D,),(2,5,3,1,):}`
C. (c) `{:(A,B,C,D,),(4,5,2,1,):}`
D. (d) `{:(A,B,C,D,),(2,1,3,5,):}`

Explanation

To solve the problem, we need to determine the number of unpaired electrons in each of the given complex ions from List-I and match them with the corresponding values from List-II.

### Step-by-Step Solution:

1. **Identify the oxidation states and electron configurations**:
- **(A) [CrF₆]⁴⁻**:
- Chromium (Cr) has an oxidation state of +2 (since F is -1 and there are 6 F atoms: -6 + x = -4, thus x = +2).
- The electron configuration of Cr is [Ar] 3d⁵ 4s¹. For Cr²⁺, it becomes [Ar] 3d⁴.
- **(B) [MnF₆]⁴⁻**:
- Manganese (Mn) has an oxidation state of +2 (similar reasoning as above).
- The electron configuration of Mn is [Ar] 3d⁵ 4s². For Mn²⁺, it becomes [Ar] 3d⁵.
- **(C) [Cr(CN)₆]⁴⁻**:
- Chromium (Cr) is again +2.
- The electron configuration remains [Ar] 3d⁴ for Cr²⁺.
- **(D) [Mn(CN)₆]⁴⁻**:
- Manganese (Mn) is +2.
- The electron configuration remains [Ar] 3d⁵ for Mn²⁺.

2. **Determine the nature of the ligands**:
- **F⁻** is a weak field ligand, which does not cause pairing of electrons.
- **CN⁻** is a strong field ligand, which causes pairing of electrons.

3. **Count the unpaired electrons**:
- **(A) [CrF₆]⁴⁻**:
- 3d⁴ with weak field ligand (F⁻): 4 unpaired electrons.
- **(B) [MnF₆]⁴⁻**:
- 3d⁵ with weak field ligand (F⁻): 5 unpaired electrons.
- **(C) [Cr(CN)₆]⁴⁻**:
- 3d⁴ with strong field ligand (CN⁻): 2 unpaired electrons (pairing occurs).
- **(D) [Mn(CN)₆]⁴⁻**:
- 3d⁵ with strong field ligand (CN⁻): 1 unpaired electron (pairing occurs).

4. **Match the results with List-II**:
- **(A) [CrF₆]⁴⁻**: 4 unpaired electrons → matches with 4.
- **(B) [MnF₆]⁴⁻**: 5 unpaired electrons → matches with 5.
- **(C) [Cr(CN)₆]⁴⁻**: 2 unpaired electrons → matches with 2.
- **(D) [Mn(CN)₆]⁴⁻**: 1 unpaired electron → matches with 1.

### Final Matching:
- A → 4
- B → 5
- C → 2
- D → 1

### Codes:
The correct matching codes would be:
- A - 4
- B - 5
- C - 2
- D - 1