If the z-axis if taken as the internuclear axis, then which of the following combinations of atomic orbitals is a nonbonding combination?

Options

A. `s` and `p_y`
B. `p_x` and `d_(yz)`
C. `p_x` and `p_y`
D. All of these

Explanation

To determine which combination of atomic orbitals is a nonbonding combination when the z-axis is taken as the internuclear axis, we need to analyze the types of atomic orbitals involved and their orientations.

### Step-by-Step Solution:

1. **Understanding Atomic Orbitals**:
- Atomic orbitals can be classified into different types: s, p, d, etc.
- The s-orbital is spherical and does not have a specific orientation.
- The p-orbitals (px, py, pz) have directional properties. For example, pz is aligned along the z-axis.

2. **Identifying Bonding and Nonbonding Combinations**:
- A bonding combination occurs when atomic orbitals overlap effectively along the internuclear axis (z-axis).
- Nonbonding combinations occur when there is no effective overlap along the internuclear axis.

3. **Analyzing Possible Combinations**:
- Combinations such as s-s, s-pz, or pz-pz will lead to bonding interactions since they can overlap along the z-axis.
- Combinations like px-py or d-orbitals that are oriented in the x or y directions will not overlap effectively along the z-axis.

4. **Conclusion**:
- The combination of atomic orbitals that is nonbonding would be those that do not align with the z-axis. For example, the combination of px and py orbitals would be a nonbonding combination since they are oriented perpendicular to the z-axis.

### Final Answer:
The nonbonding combination of atomic orbitals when the z-axis is taken as the internuclear axis is **px and py**.