If molecule `MX_3` has zero dipole moment, the sigma bonding orbitals used by M (atomic number `lt21`) are

Options

A. Pure p
B. sp hybrids
C. `sp^(2)` hybrids
D. `sp^(3)` hybrids

Answer

To determine the sigma bonding orbitals used by the central atom M in the molecule MX₃, given that it has a zero dipole moment, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Molecular Geometry**:
- The molecule MX₃ has a central atom M bonded to three identical atoms X. Since it has a zero dipole moment, this indicates that the molecule is symmetrical.

2. **Determining the Shape**:
- For a molecule with three bonding pairs and no lone pairs on the central atom, the molecular geometry is trigonal planar. This is because the three bond pairs will arrange themselves in a plane to minimize repulsion, forming a 120-degree angle between them.

3. **Identifying Hybridization**:
- The hybridization corresponding to a trigonal planar shape is sp². This means that one s orbital and two p orbitals from the central atom M combine to form three equivalent sp² hybrid orbitals.

4. **Conclusion**:
- Therefore, the sigma bonding orbitals used by M in the molecule MX₃, which has a zero dipole moment, are sp² hybrids.

### Final Answer:
The sigma bonding orbitals used by M are **sp² hybrids**.

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