The ion that is isoelectronic with `CO` is

Options

A. `CN^(-)`
B. `O_(2)^(+)`
C. `O_(2)^(-)`
D. `N_(2)^(+)`

Answer

To determine which ion is isoelectronic with carbon monoxide (CO), we need to follow these steps:

### Step 1: Calculate the total number of electrons in CO
- Carbon (C) has 6 electrons.
- Oxygen (O) has 8 electrons.
- Therefore, the total number of electrons in CO = 6 (from C) + 8 (from O) = 14 electrons.

### Step 2: Analyze the options provided
We need to check each option to see which one also has a total of 14 electrons.

#### Option 1: CN⁻
- Carbon (C) has 6 electrons.
- Nitrogen (N) has 7 electrons.
- The negative charge (−1) adds 1 more electron.
- Total = 6 (from C) + 7 (from N) + 1 (from charge) = 14 electrons.
- **Conclusion**: CN⁻ is isoelectronic with CO.

#### Option 2: O₂⁺
- Each oxygen (O) has 8 electrons.
- There are 2 oxygen atoms, so 2 × 8 = 16 electrons.
- The positive charge (−1) subtracts 1 electron.
- Total = 16 - 1 = 15 electrons.
- **Conclusion**: O₂⁺ is not isoelectronic with CO.

#### Option 3: O₂⁻
- Each oxygen (O) has 8 electrons.
- There are 2 oxygen atoms, so 2 × 8 = 16 electrons.
- The negative charge (−2) adds 2 more electrons.
- Total = 16 + 2 = 18 electrons.
- **Conclusion**: O₂⁻ is not isoelectronic with CO.

#### Option 4: N₂⁺
- Each nitrogen (N) has 7 electrons.
- There are 2 nitrogen atoms, so 2 × 7 = 14 electrons.
- The positive charge (−1) subtracts 1 electron.
- Total = 14 - 1 = 13 electrons.
- **Conclusion**: N₂⁺ is not isoelectronic with CO.

### Final Answer
The ion that is isoelectronic with CO is **CN⁻**.

---