The number of near about `90^@` angles between bond pair - bond pair of electrons in `BrF_5` is :

Options

A. 4
B. 5
C. 6
D. 8

Answer

To determine the number of near about 90-degree angles between bond pairs in BrF5, we will follow these steps:

### Step 1: Determine the Valence Electrons
Bromine (Br) has 7 valence electrons, and each fluorine (F) atom has 7 valence electrons. In BrF5, there are 5 fluorine atoms.

- **Calculation**:
- Valence electrons from Br = 7
- Valence electrons from 5 F = 5 × 1 = 5
- Total valence electrons = 7 (from Br) + 5 (from 5 F) = 12

### Step 2: Determine the Hybridization
To find the hybridization, we can use the formula:
\[ \text{Hybridization} = \frac{\text{Number of valence electrons} + \text{Number of monovalent atoms}}{2} \]

In BrF5:
- Number of valence electrons = 7 (Br) + 5 (F) = 12
- Number of monovalent atoms (F) = 5

- **Calculation**:
\[ \text{Hybridization} = \frac{12 + 5}{2} = \frac{17}{2} \]
This indicates a hybridization of \( sp^3d^2 \).

### Step 3: Determine the Geometry
The hybridization \( sp^3d^2 \) corresponds to an octahedral geometry. However, since BrF5 has one lone pair, the molecular shape is altered.

- **Shape**: The presence of one lone pair leads to a square pyramidal shape.

### Step 4: Analyze the Bond Angles
In a square pyramidal structure, the bond angles between the bond pairs of electrons can be analyzed. The four fluorine atoms in the base of the pyramid are arranged in a square plane, while the fifth fluorine is positioned above the plane.

- The angles between the bond pairs in the square plane are approximately 90 degrees.

### Step 5: Count the Near 90-Degree Angles
In the square pyramidal shape, there are:
- 4 bond pairs in the square plane, each forming angles of approximately 90 degrees with adjacent bond pairs.

- **Total Count**: Each of the four bond pairs forms a 90-degree angle with two other bond pairs, leading to a total of 4 near 90-degree angles.

### Final Answer
The number of near about 90-degree angles between bond pairs in BrF5 is **8**.

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