Question

Decrease in size from left to right in actinoid series is greater and gradual than that in lanthanoid series due to :

• A. $4f$ orbitals are penultimate
• B. $4f$ orbitals have greater shielding effect
• C. 5 f orbitals have poor shielding effect
• D. $5f$ orbitals have greater shielding effect

Answer 1

Answer: (C)

$5f$ have poor shielding effect so more will be $Z_{\text{eff }}$ At. size $\propto \frac{1}{Z_{\text{eff }}}$