manganese metal has the electronic configuration `[Ar]3d^4` in its +3 oxidation state.

Explanation

To determine if the statement about manganese having the electronic configuration `[Ar] 3d^4` in its +3 oxidation state is true or false, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number of Manganese**:
- Manganese (Mn) has an atomic number of 25.

2. **Write the Electronic Configuration of Neutral Manganese**:
- The electronic configuration for neutral manganese is:
\[ \text{Mn: } [Ar] 4s^2 3d^5 \]

3. **Determine the Electronic Configuration in the +3 Oxidation State**:
- In the +3 oxidation state, manganese loses three electrons. The electrons are removed first from the outermost shell (4s) and then from the 3d subshell.
- Remove 2 electrons from the 4s subshell and 1 electron from the 3d subshell:
\[ \text{4s: } 4s^2 \rightarrow 4s^0 \quad (\text{removing 2 electrons}) \]
\[ \text{3d: } 3d^5 \rightarrow 3d^4 \quad (\text{removing 1 electron}) \]

4. **Write the Final Electronic Configuration for Mn in +3 Oxidation State**:
- After removing the electrons, the electronic configuration for Mn in the +3 oxidation state becomes:
\[ \text{Mn}^{3+}: [Ar] 3d^4 \]

5. **Conclusion**:
- The statement that manganese metal has the electronic configuration `[Ar] 3d^4` in its +3 oxidation state is **True**.