Which of the following combination of orbitals can not form bond. (If x axis in internuclear axis)

Options

A. `s+p_(z)`
B. `s+s`
C. `p_(z)+p_(x)`
D. `d_(xy)+p_(y)`

Explanation

To determine which combinations of orbitals cannot form a bond when the x-axis is the internuclear axis, we will analyze the overlap of different types of orbitals.

### Step-by-Step Solution:

1. **Identify the Orbitals**: The question provides combinations of orbitals, which include:
- S and S
- Pz and Px
- dxy and Py

2. **Analyze S and S Orbitals**:
- Both S orbitals are spherical and can overlap effectively regardless of their orientation.
- **Conclusion**: S and S can form a bond.

3. **Analyze Pz and Px Orbitals**:
- Pz is oriented along the z-axis, while Px is oriented along the x-axis. These two orbitals are perpendicular to each other.
- Since they are perpendicular, there will be no overlap between Pz and Px.
- **Conclusion**: Pz and Px cannot form a bond.

4. **Analyze dxy and Py Orbitals**:
- The dxy orbital lies in the xy-plane, while the Py orbital is oriented along the y-axis.
- The dxy orbital can overlap with the Py orbital since they are not perpendicular and can interact sideways.
- **Conclusion**: dxy and Py can form a bond.

5. **Final Answer**: The combinations that cannot form a bond are:
- Pz and Px (Option 2)
- S and S can form a bond.
- dxy and Py can form a bond.

Therefore, the combinations that cannot form a bond are **Pz and Px**.