Which among the following is a paramagnetic compound?

Options

A. `N_2O`
B. NO
C. `N_2O_3`
D. `N_2O_4`

Answer

To determine which among the given compounds is paramagnetic, we need to analyze the sum of the valence electrons for each compound and check if it is odd or even.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- N2O
- NO
- N2O3
- N2O4

2. **Calculate Valence Electrons for Each Compound**:
- **N2O**:
- Nitrogen (N) has 5 valence electrons and there are 2 nitrogen atoms: \( 5 \times 2 = 10 \)
- Oxygen (O) has 6 valence electrons: \( 6 \)
- Total = \( 10 + 6 = 16 \) (even)

- **NO**:
- Nitrogen (N) has 5 valence electrons: \( 5 \)
- Oxygen (O) has 6 valence electrons: \( 6 \)
- Total = \( 5 + 6 = 11 \) (odd)

- **N2O3**:
- Nitrogen (N) has 5 valence electrons and there are 2 nitrogen atoms: \( 5 \times 2 = 10 \)
- Oxygen (O) has 6 valence electrons and there are 3 oxygen atoms: \( 6 \times 3 = 18 \)
- Total = \( 10 + 18 = 28 \) (even)

- **N2O4**:
- Nitrogen (N) has 5 valence electrons and there are 2 nitrogen atoms: \( 5 \times 2 = 10 \)
- Oxygen (O) has 6 valence electrons and there are 4 oxygen atoms: \( 6 \times 4 = 24 \)
- Total = \( 10 + 24 = 34 \) (even)

3. **Determine Magnetic Properties**:
- A compound is **paramagnetic** if the sum of its valence electrons is **odd** (indicating the presence of unpaired electrons).
- A compound is **diamagnetic** if the sum of its valence electrons is **even** (indicating all electrons are paired).

4. **Conclusion**:
- From the calculations:
- N2O: 16 (diamagnetic)
- NO: 11 (paramagnetic)
- N2O3: 28 (diamagnetic)
- N2O4: 34 (diamagnetic)
- Therefore, the only paramagnetic compound among the options is **NO**.

### Final Answer:
The paramagnetic compound is **NO**.