Question

Elements in which orbitals are progressively filled are called as:

• A. Transition elements
• B. Lanthanides
• C. Actinides
• D. Inert gases

Answer 1

Answer: (A), (B), (C)

The correct options are
A Transition elements
B Actinides
C Lanthanides

The Lanthanide and Actinide series make up the inner transition metals

The lanthanide series includes elements $58$ to $71$, which fill their $4f$ sublevel progressively.

The actinides are elements $90$ to $103$ and fill their $5f$ sublevel progressively.

Hence option B and C are correct.