Which of the following set of ions have the same number of electrons ?

Options

A. `Cr^(3+), Fe^(2+)`
B. `Cu^(+), Zn^(2+)`
C. `Mn^(2+), Fe^(3+)`
D. `Sc^(3+), V^(3+)`

Explanation

To determine which set of ions have the same number of electrons, we will analyze each option step by step.

### Step 1: Analyze the first option - Cr³⁺ and Fe²⁺
- **Atomic number of Cr (Chromium)**: 24
- **Electrons in neutral Cr**: 24
- **Cr³⁺**: This ion means 3 electrons are removed from Cr.
- Calculation: 24 - 3 = 21 electrons

- **Atomic number of Fe (Iron)**: 26
- **Electrons in neutral Fe**: 26
- **Fe²⁺**: This ion means 2 electrons are removed from Fe.
- Calculation: 26 - 2 = 24 electrons

**Conclusion for first option**: Cr³⁺ has 21 electrons and Fe²⁺ has 24 electrons. They do not have the same number of electrons.

### Step 2: Analyze the second option - Cu⁺ and Zn²⁺
- **Atomic number of Cu (Copper)**: 29
- **Electrons in neutral Cu**: 29
- **Cu⁺**: This ion means 1 electron is removed from Cu.
- Calculation: 29 - 1 = 28 electrons

- **Atomic number of Zn (Zinc)**: 30
- **Electrons in neutral Zn**: 30
- **Zn²⁺**: This ion means 2 electrons are removed from Zn.
- Calculation: 30 - 2 = 28 electrons

**Conclusion for second option**: Cu⁺ has 28 electrons and Zn²⁺ also has 28 electrons. They have the same number of electrons.

### Step 3: Analyze the third option - Mn²⁺ and Fe³⁺
- **Atomic number of Mn (Manganese)**: 25
- **Electrons in neutral Mn**: 25
- **Mn²⁺**: This ion means 2 electrons are removed from Mn.
- Calculation: 25 - 2 = 23 electrons

- **Fe³⁺**: This ion means 3 electrons are removed from Fe.
- Calculation: 26 - 3 = 23 electrons (since Fe has an atomic number of 26)

**Conclusion for third option**: Mn²⁺ has 23 electrons and Fe³⁺ also has 23 electrons. They have the same number of electrons.

### Step 4: Analyze the fourth option - Sc³⁺ and V³⁺
- **Atomic number of Sc (Scandium)**: 21
- **Electrons in neutral Sc**: 21
- **Sc³⁺**: This ion means 3 electrons are removed from Sc.
- Calculation: 21 - 3 = 18 electrons

- **Atomic number of V (Vanadium)**: 23
- **Electrons in neutral V**: 23
- **V³⁺**: This ion means 3 electrons are removed from V.
- Calculation: 23 - 3 = 20 electrons

**Conclusion for fourth option**: Sc³⁺ has 18 electrons and V³⁺ has 20 electrons. They do not have the same number of electrons.

### Final Conclusion
The sets of ions that have the same number of electrons are:
- **Option 2: Cu⁺ and Zn²⁺ (28 electrons)**
- **Option 3: Mn²⁺ and Fe³⁺ (23 electrons)**