Question

Among [Ti(H2O)₆]³⁺,[NiCl₄]²⁻,[CrO₄]²⁻,and [Mn(H₂O)₆]²⁺, the complex that exhibits the largest molar absorptivity in the visible region of the electronic absorption spectrum is

• A. [Ti(H₂O)₆]³⁺
• B. [NiCl₄]²⁻
• C. [CrO₄]²⁻
• D. [Mn(H₂O)₆]²⁺

Answer 1

The Correct Option is C

Among the given complexes, the one with the largest molar absorptivity in the visible region of the electronic absorption spectrum is usually the one that has the most intense d-d transitions or charge transfer absorptions. 

• [Ti(H₂O)₆]³⁺ has weak transitions in the visible region.
• [NiCl₄]²⁻ has d-d transitions that absorb light, but they are not as strong in the visible region.
• [CrO₄]²⁻ has a strong absorption due to charge transfer between the metal and ligand, which leads to the largest
• molar absorptivity in the visible region.
• [Mn(H₂O)₆]²⁺ also has weak d-d transitions in the visible region.

Therefore, the complex [CrO₄]²⁻ exhibits the largest molar absorptivity in the visible region.

Thus, the correct answer is (C).