MCQ
The elements in which electrons are progressively filled in 4f-orbital are called:
- AActinoids.
- BTransition elements.
- CLanthanoids.
- DHalogens.
Explanation:
The sixth period (n = 6) contains 32 elements and electrons enter 6s, 4f, 5d and 6p orbitals, in the order of filling up of the 4f orbitals begins with cerium (Z = 58) and ends at lutetium (Z = 71) to give the 4f-inner transition series which is called the lanthanoid series.
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