Which of the following atoms could have an expanded octet when it is the central atom in a covalent compound? a) B

b) O

c) Cl

d) F

only chlorine can expand its octet.

Explanation:

An atom can expand its octet is it has empty d orbital

the electronic configuration of given elements will be:

B : 1s2 2s2 2p1 [Valence shell n = 2 no d orbital]

O : 1s2 2s2 2p4 [Valence shell n = 2 no d orbital]

F : 1s2 2s2 2p5 [Valence shell n = 2 no d orbital]

Cl : 1s2 2s2 2p6 3s2 3p5 3d0 [Valence shell n = 2 no d orbital]

Out of given elements only chlorine has empty d orbitals in its valence shell

Thus only chlorine can expand its octet.