Question

What ion is formed when an atom of mercury (Hg) loses two electrons

Answer 1

magnesium ion  Hg2+ formed

Answer 2

Answer: $Hg^{2+}$ cation

Explanation:

Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.

The electrons are filled according to Afbau's rule in order of increasing energies and thus the electronic configuration

$Hg:80:[Xe]4f^{14}5d^{10}6s^2$

Thus when it loses two electrons, the number of protons outweigh the number of electrons and thus a positively charged ion called as cation is formed:

$Hg^{2+}:[Xe]4f^{14}5d^{10}$

Thus  $Hg^{2+}$ cation is formed when an atom of mercury (Hg) loses two electrons.