Which of the following is isoelectronic pair ?

Options

A. `ICl_(2), ClO_(2)`
B. `BrO_(2)^(-)BrF_(2)^(+)`
C. `ClO_(2), BrF`
D. `CN^(-),O_(3)`

Explanation

To determine which of the given options is an isoelectronic pair, we need to find out the total number of electrons in each species provided in the options. An isoelectronic pair consists of two species that have the same number of electrons.

### Step-by-Step Solution:

1. **Understanding Isoelectronic Species**:
- Isoelectronic species have the same number of total electrons. This can include ions and neutral atoms/molecules.

2. **Calculating Electrons for BrO2⁻**:
- Bromine (Br) has 7 valence electrons.
- Each Oxygen (O) has 6 valence electrons, and there are 2 oxygen atoms.
- Since BrO2 has a negative charge (BrO2⁻), we add 1 electron.
- Calculation:
- Total electrons = Valence electrons of Br + (2 × Valence electrons of O) + Charge
- Total electrons = 7 + (2 × 6) + 1 = 7 + 12 + 1 = 20 electrons.

3. **Calculating Electrons for BrF2⁺**:
- Bromine (Br) again has 7 valence electrons.
- Each Fluorine (F) has 7 valence electrons, and there are 2 fluorine atoms.
- Since BrF2 has a positive charge (BrF2⁺), we subtract 1 electron.
- Calculation:
- Total electrons = Valence electrons of Br + (2 × Valence electrons of F) - Charge
- Total electrons = 7 + (2 × 7) - 1 = 7 + 14 - 1 = 20 electrons.

4. **Comparing the Total Electrons**:
- Both BrO2⁻ and BrF2⁺ have 20 electrons.

5. **Conclusion**:
- Since both species have the same number of electrons, they form an isoelectronic pair. Therefore, the correct answer is **option B: BrO2⁻ and BrF2⁺**.