Question

Actinoids in general show more oxidation states than the lanthanoids. The main reason for this is:

• A. higher energy difference between 5f and 6d orbitals than between 4f and 5d orbitals
• B. lower energy difference between 5f and 6d orbitals than between 4f and 5d orbitals
• C. higher reactivity of actinoids than lanthanoids
• D. actinoids are more basic than lanthanoids

Answer 1

The correct option is B lower energy difference between 5f and 6d orbitals than between 4f and 5d orbitals

Due to this lower energy gap between $5f$ and $6d$ the outer $e^{-}$ are easily excited hence show variable oxidation state.