Which of the following species has plane tringular shape ?

Options

A. `N_3`
B. `NO_3^-`
C. `NO_2^-`
D. `CO_2`

Explanation

To determine which of the given species has a planar triangular shape, we can analyze the molecular geometry of each species based on their hybridization and the arrangement of their electron pairs.

### Step-by-Step Solution:

1. **Identify the Given Species**:
The species we need to analyze are:
- N3^-
- NO3^-
- N2O2^-
- CO2

2. **Analyze N3^- (Azide Ion)**:
- **Hybridization**: The azide ion (N3^-) has a linear structure. It is sp hybridized.
- **Shape**: The shape is linear, not planar triangular.

3. **Analyze NO3^- (Nitrate Ion)**:
- **Hybridization**: The nitrogen in NO3^- has 5 valence electrons and gains one electron, making a total of 6. It forms three bond pairs with three oxygen atoms.
- **Shape**: The hybridization is sp2, which leads to a trigonal planar shape.
- **Conclusion**: NO3^- has a planar triangular shape.

4. **Analyze N2O2^- (Dinitrogen Dioxide Ion)**:
- **Hybridization**: The nitrogen atoms in N2O2^- have 5 valence electrons each and gain electrons, leading to 6 total. It forms two bond pairs and has one lone pair.
- **Shape**: The presence of the lone pair leads to a bent or V-shaped structure, not planar triangular.

5. **Analyze CO2 (Carbon Dioxide)**:
- **Hybridization**: Carbon in CO2 has 4 valence electrons and forms two double bonds with two oxygen atoms.
- **Shape**: The hybridization is sp, which results in a linear shape.
- **Conclusion**: CO2 does not have a planar triangular shape.

6. **Final Conclusion**:
- Among the species analyzed, only **NO3^-** has a planar triangular shape.

### Final Answer:
The species with a planar triangular shape is **NO3^-**.