How many electron in an atom with atomic number `105` can have `(n + l) = 8` ?

Options

A. 15
B. 17
C. 19
D. 21

Answer

B

Explanation

The electronic configuration of element with atomic number 105 is
`1s^(2), 2s^(2) 2p^(6), 3s^(2) 3p^(6) 3d^(10), 4s^(2) 4p^(6) 4d^(10) 4f^(14), 5s^(2) 5p^(6) 5d^(10) 5f^(14), 6s^(2) 6p^(2) 6d^(3) 7s^(2)`
For `5f, (n + l) = 5 + 3 = 8`, Electrons present = 14
For `6d, (n + l) = 6 + 2 = 8`, Electrons present = 3