Explanation:
An element that gains one electron will tend to acquire a negative charge whereas an element that tend to lose an electron will acquire a positive charge.
Similarly, an element losing two electrons will acquire a 2+ charge.
For example, calcium is a group II element and has 2 valence electrons. Therefore, to attain stability it loses two electrons and thus changes into [tex]Ca^{2+}[/tex] ion.
Hence, we can conclude that an element of Group II loses two electrons in the process of a chemical combination then its ionic charge will be +2.