COMEDK202510 May 2025Evening ShiftChemistryd and f Block ElementsActual
Larger number of oxidation states are exhibited by the actinoids than those of lanthanoids. The reason is:
Options
- AHighly reactive nature of the actinoids
- BMore energy difference between 5f and 6d than between 4f and 5d orbitals
- C4f orbitals are more diffused than 5f orbitals
- DLesser energy difference between 5f and 6d than between 4f and 5d orbitals
Correct answer
D. Lesser energy difference between 5f and 6d than between 4f and 5d orbitals
Step-by-step solution
Lanthanoids exhibit primarily the +3 oxidation state because the 4f orbitals are deeply buried within the atom and are shielded by the 5s and 5p orbitals, making them less available for bonding. The energy gap between the 4f and 5d orbitals is relatively large, which restricts the participation of 4f electrons in chemical bonding. In contrast, the actinoids exhibit a wider range of oxidation states (such as +3, +4, +5, +6, and +7). This is because the 5f orbitals in actinoids are not as deeply buried as the 4f orbi