The species, having bonds angle of `120^(@)` is

Options

A. `PH_3`
B. `CIF_3`
C. `NCI_3`
D. `BCI_3`

Answer

To determine which species has a bond angle of 120 degrees, we can analyze the given compounds: pH3, ClF3, NCl3, and BCl3. The bond angle of 120 degrees is characteristic of sp2 hybridized molecules, which typically have three bond pairs and no lone pairs.

### Step-by-Step Solution:

1. **Identify the Compounds**: We are given four compounds: pH3, ClF3, NCl3, and BCl3.

2. **Determine the Hybridization**:
- **pH3 (Phosphine)**:
- Phosphorus (P) has 5 valence electrons.
- There are 3 hydrogen atoms (H) attached.
- Using the formula:
\[ \text{Steric Number} = \frac{(V + M)}{2} = \frac{(5 + 3)}{2} = 4 \]
- This indicates sp3 hybridization. Since there is one lone pair, the shape is pyramidal, and the bond angle is less than 109.5 degrees.

- **ClF3 (Chlorine Trifluoride)**:
- Chlorine (Cl) has 7 valence electrons.
- There are 3 fluorine atoms (F) attached.
- Using the formula:
\[ \text{Steric Number} = \frac{(7 + 3)}{2} = 5 \]
- This indicates sp3d hybridization. With two lone pairs, the shape is T-shaped, and the bond angle is less than 90 degrees.

- **NCl3 (Nitrogen Trichloride)**:
- Nitrogen (N) has 5 valence electrons.
- There are 3 chlorine atoms (Cl) attached.
- Using the formula:
\[ \text{Steric Number} = \frac{(5 + 3)}{2} = 4 \]
- This indicates sp3 hybridization. With one lone pair, the shape is pyramidal, and the bond angle is less than 109.5 degrees.

- **BCl3 (Boron Trichloride)**:
- Boron (B) has 3 valence electrons.
- There are 3 chlorine atoms (Cl) attached.
- Using the formula:
\[ \text{Steric Number} = \frac{(3 + 3)}{2} = 3 \]
- This indicates sp2 hybridization. With no lone pairs, the shape is trigonal planar, and the bond angle is exactly 120 degrees.

3. **Conclusion**: Among the given species, only BCl3 has a bond angle of 120 degrees due to its sp2 hybridization and the absence of lone pairs.

### Final Answer:
The species having a bond angle of 120 degrees is **BCl3**.