Question

An atom of X forms an ion according to the equation X → X⁺². 

The atomic number of the atom X is:

Options

• 16

• 10

• 12

• 14

Answer 1

12

Explanation:

X²⁺ means X loses two electrons (forms a 2+ cation). Elements that commonly form 2+ ions have two valence electrons (configuration 2, 8, 2), e.g. magnesium, atomic number 12.