Which of the following statement is false?

Options

A. of the `d^(4)` species manganese (III) is strongly reducing while `Cr^(2+)` is strongly oxiding
B. Cobalt (II) is stable in aqeous solution but in the presence of complexing reagents it is easily oxidised.
C. The `d^(1)`configuration is very unstable in ions.
D. None of these

Answer

To determine which statement is false among the given options, we need to analyze each statement regarding the properties of the d-block elements, specifically manganese and chromium.

### Step-by-Step Solution:

1. **Analyze the first statement**:
- The statement claims: "Manganese (III) is strongly reducing while Chromium (II) is strongly oxidizing."
- Manganese (III) has an electronic configuration of [Ar] 3d⁴. When it gains an electron, it becomes manganese (II) with a configuration of [Ar] 3d⁵, which is stable and thus behaves as a strong oxidizing agent.
- Chromium (II) has an electronic configuration of [Ar] 3d⁴. When it loses an electron, it becomes chromium (III) with a configuration of [Ar] 3d³, which is also stable. Therefore, chromium (II) behaves as a reducing agent.
- **Conclusion**: This statement is false.

2. **Analyze the second statement**:
- The statement claims: "Cobalt (II) is stable in aqueous solution but in the presence of a complexing reagent, it is easily oxidized."
- Cobalt (II) has an electronic configuration of [Ar] 3d⁷. It is stable in aqueous solution. However, when a strong field ligand is present, it can easily oxidize to cobalt (III) with a configuration of [Ar] 3d⁶, which is favorable for complex formation.
- **Conclusion**: This statement is true.

3. **Analyze the third statement**:
- The statement claims: "D¹ configuration is very unstable in ions."
- D¹ configuration refers to having one electron in the d-orbitals. This configuration is indeed unstable because there is a strong tendency for the ion to lose that single electron to achieve a more stable D⁰ configuration, which corresponds to a noble gas configuration.
- **Conclusion**: This statement is true.

### Final Conclusion:
- The false statement is the first one: "Manganese (III) is strongly reducing while Chromium (II) is strongly oxidizing."