The number of unpaired electron in `Mn^(4+) (Z = 25)` is :-

Options

A. Four
B. Two
C. Five
D. Three

Explanation

To find the number of unpaired electrons in the ion \( \text{Mn}^{4+} \) (with atomic number \( Z = 25 \)), we can follow these steps:

### Step 1: Determine the total number of electrons in \( \text{Mn}^{4+} \)
Manganese (Mn) has an atomic number of 25, which means it has 25 electrons in its neutral state. When it loses 4 electrons to form \( \text{Mn}^{4+} \), the total number of electrons becomes:
\[ 25 - 4 = 21 \text{ electrons} \]

### Step 2: Write the electronic configuration for 21 electrons
The electronic configuration of an atom describes how the electrons are distributed among the various atomic orbitals. For 21 electrons, the configuration is:
\[ \text{1s}^2 \, \text{2s}^2 \, \text{2p}^6 \, \text{3s}^2 \, \text{3p}^6 \, \text{3d}^3 \]
Note that the \( 4s \) orbital is filled before the \( 3d \) orbital in neutral manganese, but since \( \text{Mn}^{4+} \) loses electrons from the \( 4s \) first, we have:
\[ \text{1s}^2 \, \text{2s}^2 \, \text{2p}^6 \, \text{3s}^2 \, \text{3p}^6 \, \text{3d}^3 \]

### Step 3: Identify the number of unpaired electrons in the \( 3d \) subshell
The \( 3d \) subshell can hold a maximum of 10 electrons. In \( \text{Mn}^{4+} \), there are 3 electrons in the \( 3d \) subshell. The arrangement of these electrons in the \( 3d \) orbitals will be as follows:
- Each of the three electrons will occupy separate orbitals (due to Hund's rule) before pairing up, leading to:
\[ \text{3d}^3 \rightarrow \uparrow \, \uparrow \, \uparrow \]
This indicates that all three electrons are unpaired.

### Step 4: Conclusion
Thus, the number of unpaired electrons in \( \text{Mn}^{4+} \) is:
\[ \text{Number of unpaired electrons} = 3 \]

### Final Answer
The number of unpaired electrons in \( \text{Mn}^{4+} \) is **3**.

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