Question

The actinoids exhibit more number of oxidation states in general than the lanthanoids. This is because 

(a) the 5f orbitals extend further from the nucleus than the 4f orbitals 

(b) the 5f orbitals are more buried than the 4f orbitals 

(c) there is a similarity between 4f and 5f orbitals in their angular part of the wave function 

(d) the actinoids are more reactive than the lanthanoids.

Answer 1

Correct option(a) the 5f orbitals extend further from the nucleus than the 4f orbitals 

Explanation:

The actinoids (5f-element) exhibit more number of oxidation states in general than the lanthanoids because 5f orbitals extend farther from the nucleus than the 4f-orbitals.

Thus, the attraction on the 5f electrons in the actinoid series decreases. Hence, they can easily participate in bonding and therefore, exhibits more number of oxidation states.