`angleFAsF ` bond angle in `AsF_(3)Cl_(2)` molecule is :

Options

A. `90^(@) and 180^(@)`
B. `120^(@)`
C. `90^(@)`
D. `180^(@)`

Answer

To determine the bond angle \( \angle FAsF \) in the molecule \( AsF_3Cl_2 \), we can follow these steps:

### Step 1: Identify the Central Atom
The central atom in the molecule \( AsF_3Cl_2 \) is arsenic (As).

### Step 2: Determine the Valence Electrons
Arsenic belongs to group 15 of the periodic table and has 5 valence electrons.

### Step 3: Count the Surrounding Atoms
In \( AsF_3Cl_2 \), arsenic is bonded to three fluorine atoms and two chlorine atoms.

### Step 4: Calculate the Steric Number
The steric number is calculated as the number of sigma bonds plus the number of lone pairs on the central atom. Here, arsenic forms:
- 3 sigma bonds with fluorine
- 2 sigma bonds with chlorine

Thus, the steric number is:
\[ \text{Steric Number} = 3 (\text{F}) + 2 (\text{Cl}) + 0 (\text{lone pairs}) = 5 \]

### Step 5: Determine the Hybridization
A steric number of 5 corresponds to \( sp^3d \) hybridization, which indicates a trigonal bipyramidal geometry.

### Step 6: Identify the Positions of Atoms
In a trigonal bipyramidal geometry:
- The axial positions (180° apart) are occupied by the most electronegative atoms (in this case, fluorine).
- The equatorial positions (120° apart) are occupied by the less electronegative atoms (chlorine).

### Step 7: Determine the Bond Angles
In this geometry:
- The bond angles between axial atoms (F-As-F) are 180°.
- The bond angles between equatorial atoms (Cl-As-Cl) are 120°.
- The bond angles between axial and equatorial atoms (F-As-Cl) are 90°.

### Step 8: Conclusion
Thus, the bond angle \( \angle FAsF \) is 180°.

### Final Answer
The bond angle \( \angle FAsF \) in the molecule \( AsF_3Cl_2 \) is **180 degrees**.

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