Which of the following molecules is isoelectronic with `N_2O` ?

Options

A. `NH_2`
B. `H_2O`
C. `NO_2`
D. `CO_2`

Explanation

To determine which of the following molecules is isoelectronic with \( N_2O \), we need to first calculate the total number of electrons in \( N_2O \).

### Step 1: Calculate the number of electrons in \( N_2O \)
- **Nitrogen (N)** has 7 electrons, and there are 2 nitrogen atoms in \( N_2O \).
- **Oxygen (O)** has 8 electrons, and there is 1 oxygen atom in \( N_2O \).

The total number of electrons can be calculated as follows:
\[ \text{Total electrons in } N_2O = (2 \times 7) + (1 \times 8) = 14 + 8 = 22 \text{ electrons} \]

### Step 2: Identify the molecules provided in the options and calculate their total electrons
1. **For \( NH_2 \)**:
- Nitrogen: 7 electrons
- Hydrogen: 1 electron (2 atoms)
\[ \text{Total electrons in } NH_2 = 7 + (2 \times 1) = 7 + 2 = 9 \text{ electrons} \]

2. **For \( H_2O \)**:
- Oxygen: 8 electrons
- Hydrogen: 1 electron (2 atoms)
\[ \text{Total electrons in } H_2O = 8 + (2 \times 1) = 8 + 2 = 10 \text{ electrons} \]

3. **For \( NO_2 \)**:
- Nitrogen: 7 electrons
- Oxygen: 8 electrons (2 atoms)
\[ \text{Total electrons in } NO_2 = 7 + (2 \times 8) = 7 + 16 = 23 \text{ electrons} \]

4. **For \( CO_2 \)**:
- Carbon: 6 electrons
- Oxygen: 8 electrons (2 atoms)
\[ \text{Total electrons in } CO_2 = 6 + (2 \times 8) = 6 + 16 = 22 \text{ electrons} \]

### Step 3: Compare the total number of electrons
Now, we compare the total number of electrons in each molecule with \( N_2O \):
- \( N_2O \): 22 electrons
- \( NH_2 \): 9 electrons (not isoelectronic)
- \( H_2O \): 10 electrons (not isoelectronic)
- \( NO_2 \): 23 electrons (not isoelectronic)
- \( CO_2 \): 22 electrons (isoelectronic)

### Conclusion
The molecule that is isoelectronic with \( N_2O \) is \( CO_2 \).

### Final Answer
The correct answer is \( CO_2 \).

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