Which of the following orbital (s) cannot form `delta`-bond ?

Options

A. `d_(x^(2)-y^(2))`-orbitals
B. `d_(xy)`-orbital
C. `d_(z^(2))`-orbital
D. `p_(x)`-orbital

Answer

To determine which of the following orbitals cannot form a delta bond, we need to understand the conditions required for delta bond formation. A delta bond is formed by the overlap of four lobes of orbitals. Let's analyze the given orbitals step by step.

### Step-by-Step Solution:

1. **Understanding Delta Bond Formation**:
- A delta bond is formed by the lateral overlap of orbitals that have four lobes. This means that for a delta bond to exist, the orbitals must be able to align in such a way that all four lobes can overlap simultaneously.

2. **Analyzing the Orbitals**:
- **dx² - y² Orbital**:
- The dx² - y² orbital has four lobes oriented along the x and y axes. When two dx² - y² orbitals approach each other, they can overlap in such a way that they form a delta bond. **(Can form a delta bond)**

- **dxy Orbital**:
- The dxy orbital also has four lobes, oriented in the x-y plane. When two dxy orbitals approach each other, they can overlap to form a delta bond. **(Can form a delta bond)**

- **dz² Orbital**:
- The dz² orbital has a different shape, consisting of two lobes along the z-axis and a ring of electron density in the x-y plane. Since it does not have four lobes that can overlap, it cannot form a delta bond. **(Cannot form a delta bond)**

- **px Orbital**:
- The px orbital has two lobes along the x-axis. Similar to the dz² orbital, it does not have four lobes for overlap and therefore cannot form a delta bond. **(Cannot form a delta bond)**

3. **Conclusion**:
- The orbitals that cannot form a delta bond are **dz² and px** orbitals.

### Final Answer:
The orbitals that cannot form a delta bond are **dz² and px**.