Explanation:

Anhydrous CuSO₄ Solution:
- Anhydrous CuSO₄ is a white crystalline solid.
- When dissolved in water, it forms a blue-colored solution due to the presence of Cu²⁺ ions.
- The blue color is a result of the absorption of certain wavelengths of light by the Cu²⁺ ions, leading to the reflection of blue light.

Ammonical CuSO₄ Solution:
- When ammonia is added to the aqueous solution of CuSO₄, it forms a deep blue-colored solution.
- The ammonia molecules coordinate with the Cu²⁺ ions, forming a complex ion known as [Cu(NH₃)₄]²⁺.
- This complex ion has a different structure compared to the Cu²⁺ ions in the aqueous solution, resulting in a deeper blue color.
- The coordination of ammonia with the Cu²⁺ ions also affects the absorption and reflection of light, leading to the observed deep blue color.
In conclusion, the difference in color between the aqueous solution of anhydrous CuSO₄ and its ammonical solution can be attributed to the formation of a complex ion with ammonia, which alters the structure and properties of the Cu²⁺ ions in the solution.