Is `pi-MO` weaker or stronger than `sigma-MO`?

Explanation

To determine whether pi molecular orbitals (π-MOs) are weaker or stronger than sigma molecular orbitals (σ-MOs), we need to analyze the formation and characteristics of each type of molecular orbital.

### Step-by-Step Solution:

1. **Understanding Sigma Molecular Orbitals (σ-MOs):**
- Sigma molecular orbitals are formed by the head-on (end-to-end) overlapping of atomic orbitals.
- For example, consider the formation of the σ2p_x molecular orbital. When two 2p_x orbitals from different atoms overlap directly along the internuclear axis, they create a σ bond.
- This type of overlapping results in a significant extent of overlap, which leads to a strong bond.
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