Q83 / 200 · NEET 2022 (Phase 2) · Chemistry

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

  • A
    $4 f$ orbitals are penultimate
  • B
    $4 f$ orbitals have greater shielding effect
  • Correct answer
    C
    $5 f$ orbitals have poor shielding effect
  • D
    $5 \mathrm{f}$ orbitals have greater shielding effect

Solution

More is the number of poor shielders, greater will be $\mathrm{Z}_{\text {eff }}$ and hence, smaller is the size. Actinoids consists of more no. of poor shielders $(3 d, 4 d, 5 d, 4 f)$. Therefore, size continuously decreases left to right.

Hence, the correct answer is option: 'C'.

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