`Sc^(3+)` is colourless is aqueous solution whereas `Ti^(3+)` is coloured.

Explanation

To understand why Sc^(3+) is colorless in aqueous solution while Ti^(3+) is colored, we need to analyze their electronic configurations and the concept of unpaired electrons.

### Step-by-Step Solution:

1. **Identify the Electronic Configuration of Scandium (Sc) and Titanium (Ti):**
- Scandium (Sc) has an atomic number of 21. Its ground state electronic configuration is:
\[
\text{Sc: } [Ar] 3d^1 4s^2
...