Total number of angle in `SeCl_(4)` which are less than `90^(@)`.

Explanation

To determine the total number of angles in \( \text{SeCl}_4 \) that are less than \( 90^\circ \), we first need to analyze the molecular geometry of the compound.

### Step 1: Determine the Lewis Structure of \( \text{SeCl}_4 \)

1. **Count the Valence Electrons**:
- Selenium (Se) has 6 valence electrons.
- Each Chlorine (Cl) has 7 valence electrons, and there are 4 Cl atoms.
- Total valence electrons = \( 6 + (4 \times 7) = 6 + 28 = 34 \) electrons.

2. **Draw the Lewis Structure**:
- Place Se in the center and surround it with 4 Cl atoms.
- Form single bonds between Se and each Cl atom, using 8 electrons (4 bonds).
- Distribute the remaining 26 electrons as lone pairs on Cl atoms (3 lone pairs on each Cl).

### Step 2: Determine the Molecular Geometry

1. **Identify the Steric Number**:
- The steric number is the number of bonded atoms plus the number of lone pairs around the central atom.
- In \( \text{SeCl}_4 \), there are 4 bonded Cl atoms and no lone pairs on Se.
- Steric number = \( 4 + 0 = 4 \).

2. **Determine the Geometry**:
- A steric number of 4 corresponds to a tetrahedral arrangement of electron pairs.
- However, since all bonds are single bonds, the actual molecular shape is also tetrahedral.

### Step 3: Analyze the Bond Angles

1. **Identify Bond Angles**:
- In a perfect tetrahedral geometry, the bond angles are \( 109.5^\circ \).
- However, due to the presence of lone pairs, the angles can be affected.

2. **Determine Angles Less Than \( 90^\circ \)**:
- In a tetrahedral arrangement, the angles between the bonds are typically greater than \( 90^\circ \).
- Since there are no lone pairs on the central atom (Se), all angles remain close to \( 109.5^\circ \).

### Conclusion

- Since there are no angles in \( \text{SeCl}_4 \) that are less than \( 90^\circ \), the total number of angles in \( \text{SeCl}_4 \) that are less than \( 90^\circ \) is **0**.

### Final Answer
**Total number of angles in \( \text{SeCl}_4 \) which are less than \( 90^\circ \) = 0.**

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