Question

Actinoid contraction is more than lanthanoid contraction because:

• A. energy of 4f and 5f orbitals are same
• B. 5f orbitals are more diffused as compared to 4f orbitals
• C. actinoids show greater range of oxidation states than lanthanoids
• D. actinoids are highly reactive

Answer 1

The correct option is B 5f orbitals are more diffused as compared to 4f orbitals

$5f$ orbitals are bigger than $4f$ orbitals, in other words, $5f$ orbitals are more diffused thereby having the poor shielding effect. Hence have a more effective nuclear charge thereby having a small size.

Hence actinide contraction is more than lanthanide contraction.