Which of the following species must have maximum number of electrons in '`d_(xy)'` orbital?

Options

A. Cr
B. `Fe^(3+)`
C. `Cu^(+)`
D. Both (a) and (b)

Answer

To determine which species has the maximum number of electrons in the `d_(xy)` orbital, we will analyze the electronic configurations of the given species: Chromium, Iron (Fe³⁺), and Copper (Cu⁺).

### Step 1: Determine the electronic configuration of each species.

1. **Chromium (Cr)**:
- Atomic number = 24
- Electronic configuration: \( \text{Ar} \, 4s^1 \, 3d^5 \)
- In the 3d subshell, the distribution of electrons is as follows:
- \( d_{xy} \): 1 electron
- \( d_{yz} \): 1 electron
- \( d_{zx} \): 1 electron
- \( d_{x^2-y^2} \): 1 electron
- \( d_{z^2} \): 1 electron
- Total in `d_(xy)` = 1

2. **Iron (Fe³⁺)**:
- Atomic number = 26
- Neutral Iron configuration: \( \text{Ar} \, 4s^2 \, 3d^6 \)
- For Fe³⁺, after losing 3 electrons (2 from 4s and 1 from 3d):
- Configuration: \( \text{Ar} \, 3d^5 \)
- Distribution in 3d:
- \( d_{xy} \): 1 electron
- \( d_{yz} \): 1 electron
- \( d_{zx} \): 1 electron
- \( d_{x^2-y^2} \): 1 electron
- \( d_{z^2} \): 1 electron
- Total in `d_(xy)` = 1

3. **Copper (Cu⁺)**:
- Atomic number = 29
- Neutral Copper configuration: \( \text{Ar} \, 4s^1 \, 3d^{10} \)
- For Cu⁺, after losing 1 electron (from 4s):
- Configuration: \( \text{Ar} \, 3d^{10} \)
- Distribution in 3d:
- \( d_{xy} \): 2 electrons
- \( d_{yz} \): 2 electrons
- \( d_{zx} \): 2 electrons
- \( d_{x^2-y^2} \): 2 electrons
- \( d_{z^2} \): 2 electrons
- Total in `d_(xy)` = 2

### Step 2: Compare the number of electrons in the `d_(xy)` orbital for each species.

- Chromium (Cr): 1 electron in `d_(xy)`
- Iron (Fe³⁺): 1 electron in `d_(xy)`
- Copper (Cu⁺): 2 electrons in `d_(xy)`

### Conclusion:
The species with the maximum number of electrons in the `d_(xy)` orbital is **Copper (Cu⁺)**, which has **2 electrons** in that orbital.

### Final Answer:
**Copper (Cu⁺)** has the maximum number of electrons in the `d_(xy)` orbital.

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