Which of the following molecular orbitals has two nodal planes ?

Options

A. `sigma _(2s) ^(**)`
B. `pi _(2py)^(**)`
C. `pi _(2py)`
D. `pi _(2px)`

Explanation

To determine which molecular orbital has two nodal planes, we need to understand the concept of nodal planes and how they relate to molecular orbitals.

### Step-by-Step Solution:

1. **Define Nodal Plane**: A nodal plane is a region in a molecular orbital where the probability of finding an electron is zero. This means that the electron density in this plane is absent.

2. **Identify the Molecular Orbitals**: We need to consider the molecular orbitals in question. Common molecular orbitals include:
- Sigma (σ) and sigma star (σ*)
- Pi (π) and pi star (π*)

3. **Analyze Sigma Star 2s Orbital**: The σ* 2s orbital is an anti-bonding molecular orbital formed from the destructive interference of two 2s atomic orbitals. This orbital has one nodal plane, where the electron density is zero.

4. **Analyze Pi Star 2py Orbital**: The π* 2py orbital is formed from the combination of two 2p orbitals (2p_y). This orbital has two nodal planes that are perpendicular to each other. One nodal plane is located in the xy-plane, and the other is in the xz-plane.

5. **Compare Other Orbitals**:
- The π 2px orbital is a bonding molecular orbital and has one nodal plane.
- The σ 2p orbital is also a bonding orbital and has no nodal planes.

6. **Conclusion**: Among the molecular orbitals discussed, the π* 2py orbital is the one that has two nodal planes.

### Final Answer:
The molecular orbital with two nodal planes is **π* 2py**.

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