Which have maximum paramagnetism in `M^(3+)` ion for Lanthanoid (spin only ) ?

Explanation

To determine which lanthanoid ion, specifically \( M^{3+} \), has the maximum paramagnetism, we need to analyze the electronic configurations of the lanthanoid elements and identify the one with the highest number of unpaired electrons.

### Step-by-Step Solution:

1. **Understanding Paramagnetism**:
- Paramagnetism arises from the presence of unpaired electrons in an atom or ion. The more unpaired electrons, the stronger the paramagnetic behavior.

2. **Identify the Lanthanoids**:
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