The molecule which has pyramidal shape is

Options

A. `PCI_3`
B. `SO_2`
C. `CO_(3)^(2-)`
D. `NO_(3)^(-)`

Answer

To determine which molecule has a pyramidal shape, we will analyze the given options one by one, focusing on their hybridization and molecular geometry.

### Step 1: Analyze PCl3O (Phosphorus Trichloride Oxide)
1. **Valence Electrons**: Phosphorus (P) has 5 valence electrons, and each chlorine (Cl) has 7 valence electrons. Therefore, for PCl3O:
- P: 5 electrons
- 3 Cl: 3 × 7 = 21 electrons
- O: 6 electrons
- Total = 5 + 21 + 6 = 32 electrons
2. **Lone Pairs**: Phosphorus will have one lone pair after forming bonds with three chlorine atoms and one oxygen atom.
3. **Sigma Bonds**: There are 3 sigma bonds with Cl and 1 with O, totaling 4 sigma bonds.
4. **Steric Number**: The steric number is the number of sigma bonds plus lone pairs = 4 (3 sigma + 1 lone pair).
5. **Hybridization**: The hybridization is sp³.
6. **Molecular Shape**: With one lone pair, the shape is trigonal pyramidal.

### Step 2: Analyze SO2 (Sulfur Dioxide)
1. **Valence Electrons**: Sulfur (S) has 6 valence electrons, and each oxygen (O) has 6 valence electrons:
- S: 6 electrons
- 2 O: 2 × 6 = 12 electrons
- Total = 6 + 12 = 18 electrons
2. **Lone Pairs**: Sulfur has one lone pair after forming bonds with two oxygen atoms.
3. **Sigma Bonds**: There are 2 sigma bonds.
4. **Steric Number**: The steric number is 2 (2 sigma bonds) + 1 (lone pair) = 3.
5. **Hybridization**: The hybridization is sp².
6. **Molecular Shape**: The shape is bent due to the lone pair-bond pair repulsion.

### Step 3: Analyze CO3²⁻ (Carbonate Ion)
1. **Valence Electrons**: Carbon (C) has 4 valence electrons, and each oxygen (O) has 6 valence electrons:
- C: 4 electrons
- 3 O: 3 × 6 = 18 electrons
- 2 extra electrons for the 2- charge.
- Total = 4 + 18 + 2 = 24 electrons
2. **Lone Pairs**: There are no lone pairs on carbon.
3. **Sigma Bonds**: There are 3 sigma bonds.
4. **Steric Number**: The steric number is 3 (3 sigma bonds) + 0 (lone pairs) = 3.
5. **Hybridization**: The hybridization is sp².
6. **Molecular Shape**: The shape is trigonal planar.

### Step 4: Analyze NO3⁻ (Nitrate Ion)
1. **Valence Electrons**: Nitrogen (N) has 5 valence electrons, and each oxygen (O) has 6 valence electrons:
- N: 5 electrons
- 3 O: 3 × 6 = 18 electrons
- 1 extra electron for the -1 charge.
- Total = 5 + 18 + 1 = 24 electrons
2. **Lone Pairs**: There are no lone pairs on nitrogen.
3. **Sigma Bonds**: There are 3 sigma bonds.
4. **Steric Number**: The steric number is 3 (3 sigma bonds) + 0 (lone pairs) = 3.
5. **Hybridization**: The hybridization is sp².
6. **Molecular Shape**: The shape is trigonal planar.

### Conclusion
After analyzing all the given molecules, we find that the only molecule with a pyramidal shape is **PCl3O**.

**Final Answer**: The molecule which has a pyramidal shape is **PCl3O**.

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