Explain why a knowledge of magnetic suceptilbility of a complex is often necessary for a correct assignment of the electronic conifiguration according to valence bond theory.

Explanation

To explain why knowledge of magnetic susceptibility of a complex is often necessary for a correct assignment of the electronic configuration according to valence bond theory, we can break it down into several steps:

### Step-by-Step Solution:

1. **Understanding Magnetic Susceptibility**:
- Magnetic susceptibility is a measure of how much a material will become magnetized in an applied magnetic field. It indicates whether a complex is paramagnetic (contains unpaired electrons) or diamagnetic (contains all paired electrons).

2. **Relation to Electronic Configuration**:
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