Both `Cr^(3+)` and `Pt^(4+)` have a coordination number of 6 Which of the following pairs of complexes will show approximately the same electrical conductance for their `0.1M` aqueous solutions ?

Options

A. a)`CrCI_(3).4NH_(3)andPtCI_(4).4NH_(3)`
B. b)`CrCI_(3).3NH_(3)andPtCI_(4).5NH_(3)`
C. c)`CrCI_(3).6NH_(3)andPtCI_(4).5NH_(3)`
D. d)`CrCI_(3).5NH_(3)andPtCI_(4).5NH_(3)`

Answer

To solve the problem of determining which pairs of complexes will show approximately the same electrical conductance for their 0.1M aqueous solutions, we need to analyze the number of ions produced when these complexes dissociate in solution. The electrical conductance of a solution is directly related to the number of ions present; more ions lead to higher conductance.

### Step-by-Step Solution:

1. **Identify the Coordination Complexes**:
We have two metal ions, `Cr^(3+)` and `Pt^(4+)`, both with a coordination number of 6. We need to analyze the given pairs of complexes to see how many ions each produces when dissolved in water.

2. **Analyze Each Complex**:
Let's denote the complexes as follows:
- Complex A: `Cr(NH3)4Cl2`
- Complex B: `Pt(NH3)4Cl2`
- Complex C: `Cr(NH3)3Cl3`
- Complex D: `Pt(NH3)5Cl`
- Complex E: `Cr(NH3)5Cl`
- Complex F: `Pt(NH3)5Cl3`

3. **Dissociation of Each Complex**:
- For Complex A (`Cr(NH3)4Cl2`):
- Dissociates into: `Cr^(3+)` + 2 `Cl^-`
- Total ions = 1 + 2 = 3 ions.

- For Complex B (`Pt(NH3)4Cl2`):
- Dissociates into: `Pt^(4+)` + 2 `Cl^-`
- Total ions = 1 + 2 = 3 ions.

- For Complex C (`Cr(NH3)3Cl3`):
- Dissociates into: `Cr^(3+)` + 3 `Cl^-`
- Total ions = 1 + 3 = 4 ions.

- For Complex D (`Pt(NH3)5Cl`):
- Dissociates into: `Pt^(4+)` + `Cl^-`
- Total ions = 1 + 1 = 2 ions.

- For Complex E (`Cr(NH3)5Cl`):
- Dissociates into: `Cr^(3+)` + `Cl^-`
- Total ions = 1 + 1 = 2 ions.

- For Complex F (`Pt(NH3)5Cl3`):
- Dissociates into: `Pt^(4+)` + 3 `Cl^-`
- Total ions = 1 + 3 = 4 ions.

4. **Compare the Total Number of Ions**:
- Complex A and Complex B both produce 3 ions.
- Complex C produces 4 ions.
- Complex D and Complex E both produce 2 ions.
- Complex F produces 4 ions.

5. **Conclusion**:
The pairs of complexes that show approximately the same electrical conductance are:
- Complex A (`Cr(NH3)4Cl2`) and Complex B (`Pt(NH3)4Cl2`), both producing 3 ions.
- Complex C (`Cr(NH3)3Cl3`) and Complex F (`Pt(NH3)5Cl3`), both producing 4 ions.

Thus, the answer to the question is **Option C** (Complex C and Complex F).