Oxidation state of nitrogen in `H-N equiv C` is

Options

A. -4
B. `+3`
C. -3
D. -2

Answer

To determine the oxidation state of nitrogen in the compound H-N≡C (hydrogen cyanide), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Elements and Their Bonds**:
- The compound consists of hydrogen (H), nitrogen (N), and carbon (C).
- The structure is H-N≡C, indicating a triple bond between nitrogen and carbon.

2. **Determine Electronegativity**:
- The electronegativity values are:
- Hydrogen (H): 2.1
- Carbon (C): 2.5
- Nitrogen (N): 3.0
- Since nitrogen is the most electronegative, it will attract electrons more strongly than both hydrogen and carbon.

3. **Analyze the Bonds**:
- In the triple bond (N≡C), nitrogen will have a greater share of the bonding electrons, effectively giving it a partial negative charge.
- In the single bond (H-N), nitrogen will again attract the bonding electrons towards itself, leading to a partial negative charge.

4. **Assign Charges Based on Bonding**:
- For the triple bond (N≡C):
- Nitrogen is more electronegative than carbon, thus it can be considered to have a charge of -3 (since it effectively "gains" three electrons).
- Carbon, being less electronegative, will have a charge of +3.
- For the single bond (H-N):
- Nitrogen is more electronegative than hydrogen, so nitrogen will take the bonding electron, resulting in a charge of -1 for nitrogen and +1 for hydrogen.

5. **Calculate the Overall Charge on Nitrogen**:
- From the triple bond with carbon, nitrogen has a charge of -3.
- From the single bond with hydrogen, nitrogen has an additional charge of -1.
- Therefore, the total charge on nitrogen is:
\[ -3 \text{ (from N≡C)} + (-1) \text{ (from H-N)} = -4 \]

6. **Conclusion**:
- The oxidation state of nitrogen in H-N≡C is -4.

### Final Answer:
The oxidation state of nitrogen in H-N≡C is -4.