When the number of electron pairs on the central atom is six, the geometry of the molecule is :

Options

A. Octahedral
B. Trigonal bipyramidal
C. Equilateral triangle
D. Linear

Answer

To determine the geometry of a molecule when the number of electron pairs on the central atom is six, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Number of Electron Pairs**:
- The question states that there are 6 electron pairs on the central atom.

2. **Understand Electron Pair Geometry**:
- In VSEPR (Valence Shell Electron Pair Repulsion) theory, the arrangement of electron pairs around a central atom determines the molecular geometry.

3. **Determine the Geometry for 6 Electron Pairs**:
- When there are 6 electron pairs, the electron pair geometry is octahedral. This is because the pairs will arrange themselves to minimize repulsion, leading to an octahedral shape.

4. **Consider the Bonding and Lone Pairs**:
- If we assume that all 6 pairs are bond pairs (as in an AB6 type molecule), there are no lone pairs affecting the geometry. This reinforces the octahedral shape.

5. **Visualize the Octahedral Geometry**:
- In an octahedral geometry, the central atom is at the center, and the surrounding atoms are positioned at the corners of an octahedron. This results in bond angles of 90 degrees between adjacent bonds.

6. **Conclusion**:
- Based on the above reasoning, when the number of electron pairs on the central atom is six, the geometry of the molecule is octahedral.

### Final Answer:
The geometry of the molecule when the number of electron pairs on the central atom is six is **octahedral**.

---