Question

The penultimate shell can have maximum how many electrons?

a) 2
b) 8
c) 18
d) 32

Plz give answer with explanation......

Answer 1

18 . Because a penultimate shell has 18 electrons while an anti penultimate shell have 32 electrons.

Answer 2

The penultimate shell can have maximum 18 electrons.

• At first, the Penultimate shell is the shell next to the outermost shell.
• The principal quantum number n= 1 has only s orbital, n=2 has s and p orbitals, n=3 has s, p and d orbitals and so on.
• s orbital have 1 space, p has 3 spaces, d has 5 spaces, and f has 7 spaces.
• An orbital can have a maximum of only two electrons and must have opposite spins.
• Hence, s-orbital= (1 x 2)= 2, p- orbitals = (3 x 2)= 6, d- orbital= (5 x 2)= 10 and f- orbital = (7 x 2) = 14.
• If both the s and p orbitals are full the number of electrons is (2+6)= 8
• If s, p and d orbitals are filled, the number of electrons is (2+6+10) = 18.
• If f is the outer most orbital it will have s, p and d full, so the maximum electron obtained by the penultimate shell will be 18.

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