The `f`-block elements of the periodic table contains those element in which

Options

A. Only `4f` orbitals are progressively filled in 6th period.
B. only `5f` orbtials are progressively filled in 7th period.
C. `4f` and `5f` orbitals are progressively filled in 6th and 7th periods respectively.
D. None of these

Answer

C

Explanation

Electronic configuration of `f`-block element `(n - 2) f^(1-14)`,
`(n - 1) d^(10) , ns^(2) f`-block starts with 6th period `(n = 6)`.