`La^(3+)(Z=57)` and `Lu^(3+)(Z=71)` do not show any colour in solution. Assign reason.

Explanation

To understand why La^(3+) (lanthanum in the +3 oxidation state) and Lu^(3+) (lutetium in the +3 oxidation state) do not show any color in solution, we can analyze their electronic configurations and the concept of unpaired electrons.

### Step-by-Step Solution:

1. **Identify the Oxidation States**:
- La^(3+) and Lu^(3+) refer to lanthanum and lutetium in the +3 oxidation state.

2. **Determine the Atomic Numbers**:
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