Question

More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is

(a) more active nature of the actinoids

(b) more energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals

(c) lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals

(d) greater metallic character of the lanthanoids than that of the corresponding actinoids.

Answer 1

Correct option (c) lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals

Explanation :

The 5f orbitals extend into space beyond the 6s and 6p-orbitals and participate in bonding.

This is in direct contrast to the lanthanides where the 4f-orbitals are buried deep inside in the atom, totally shielded by outer orbitals and thus unable to take part in bonding.