Explain why Pd²⁺(aq) appears brown while Cd²⁺ appears colorless.

• A. Pd²⁺(aq) appears brown, while Cd²⁺ appears colorless because electrons in Pd²⁺ can be promoted to higher energy d orbitals by absorbing light.
• B. Pd²⁺(aq) appears brown, while Cd²⁺ appears colorless because electrons in Cd²⁺ can be promoted to higher energy d orbitals by absorbing all colors.
• C. Pd²⁺(aq) appears brown while Cd²⁺ appears colorless because the d orbitals in Pd²⁺ are completely filled, and the electrons can be promoted to higher energy d orbitals by absorbing light.
• D. Pd²⁺(aq) appears brown, while Cd²⁺ appears colorless because the d orbitals in Cd²⁺ are completely filled, and the electrons can be promoted to higher energy orbitals by absorbing all colors.

Answer: (A)