The element that can show an expanded octet in the list is Br.
Bromine has an electron configuration of [Ar] 3d¹⁰ 4s² 4p⁵. This means that still has accessible 4d orbitals to which electrons can be filled. This is the reason why it is able to expand its octet.
Recall that any element that has accessible higher energy orbitals to which electrons can be filled can easily expand its octet. Generally, first and second period elements do not expand their octet.
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