Which of the given ion below is isoelectronic with `CO_2` ?

Options

A. `N_2^+`
B. `N_2O`
C. `O_2^+`
D. `O_2^-`

Answer

To find which ion is isoelectronic with \( CO_2 \), we need to determine the number of electrons in \( CO_2 \) and compare it with the given ions.

### Step-by-Step Solution:

1. **Calculate the number of electrons in \( CO_2 \)**:
- Carbon (C) has an atomic number of 6, which means it has 6 electrons.
- Oxygen (O) has an atomic number of 8, which means it has 8 electrons.
- Since \( CO_2 \) has one carbon atom and two oxygen atoms, we calculate the total number of electrons as follows:
\[ \text{Total electrons in } CO_2 = \text{Electrons from C} + 2 \times \text{Electrons from O} = 6 + 2 \times 8 = 6 + 16 = 22 \]

2. **Check the options for isoelectronic ions**:
- We need to find an ion that also has 22 electrons.

3. **Evaluate each option**:
- **Option 1: \( N_2^+ \)**
- Nitrogen (N) has an atomic number of 7. For \( N_2 \):
\[ \text{Total electrons} = 2 \times 7 - 1 = 14 - 1 = 13 \]
- This is not isoelectronic with \( CO_2 \).

- **Option 2: \( N_2 \)**
- For \( N_2 \):
\[ \text{Total electrons} = 2 \times 7 = 14 \]
- This is not isoelectronic with \( CO_2 \).

- **Option 3: \( O_2^+ \)**
- For \( O_2 \):
\[ \text{Total electrons} = 2 \times 8 - 1 = 16 - 1 = 15 \]
- This is not isoelectronic with \( CO_2 \).

- **Option 4: \( O_2^- \)**
- For \( O_2 \):
\[ \text{Total electrons} = 2 \times 8 + 1 = 16 + 1 = 17 \]
- This is not isoelectronic with \( CO_2 \).

4. **Conclusion**:
- None of the provided options are isoelectronic with \( CO_2 \). However, if we consider \( N_2O \) as mentioned in the video transcript, we can calculate:
- For \( N_2O \):
\[ \text{Total electrons} = 2 \times 7 + 8 = 14 + 8 = 22 \]
- Therefore, \( N_2O \) is isoelectronic with \( CO_2 \).

### Final Answer:
The ion that is isoelectronic with \( CO_2 \) is \( N_2O \).