If Mg²⁺has 12 protons and 12 neutrons, what is its atomic number and mass number?

Atomic number: It is defined as the number of protons present in the atom of an element.

Mass number: It is defined as the sum of number of protons and neutrons present in the atom of an element.

The number of protons in Mg²⁺ = 12, number of neutrons = 12

Therefore, the atomic number = number of protons= 12.

Mass number = number of protons + number of neutrons

= 12 + 12 = 24.