The `ONO` bond angle is maximum in

Options

A. `NO_(3)^(-)`
B. `NO_(2)^(-)`
C. `NO_(2)`
D. `NO_(2)^(+)`

Explanation

To determine where the `ONO` bond angle is maximum, we need to analyze the molecular structures of the given compounds. The compounds in question are related to nitrogen oxides, specifically NO3-, NO2-, NO2, and NO2+.

### Step-by-Step Solution:

1. **Identify the Structures**:
- **A. NO3- (Nitrate Ion)**: The structure consists of one nitrogen atom bonded to three oxygen atoms, with one double bond and two single bonds. The nitrogen is sp² hybridized, leading to a bond angle of approximately 120 degrees.
- **B. NO2- (Nitrite Ion)**: The structure has one nitrogen atom bonded to two oxygen atoms, with one double bond and one single bond. The nitrogen has a lone pair, leading to increased repulsion and a bond angle of approximately 115 degrees. The hybridization is also sp².
- **C. NO2 (Nitrogen Dioxide)**: This molecule has one nitrogen atom bonded to two oxygen atoms, both with double bonds. It has a free radical, and the bond angle is around 134 degrees. The hybridization is sp².
- **D. NO2+ (Nitronium Ion)**: The structure consists of one nitrogen atom bonded to two oxygen atoms, both with double bonds, and no lone pairs on nitrogen. The hybridization is sp, leading to a linear structure with a bond angle of 180 degrees.

2. **Compare Bond Angles**:
- NO3- has a bond angle of approximately 120 degrees.
- NO2- has a bond angle of approximately 115 degrees.
- NO2 has a bond angle of approximately 134 degrees.
- NO2+ has a bond angle of 180 degrees.

3. **Conclusion**:
- The bond angle is maximum in the case of NO2+, which has a linear structure with a bond angle of 180 degrees.

### Final Answer:
The `ONO` bond angle is maximum in **NO2+**.