Answer:
Ca(2+)
Explanation:
Sodium (Na) only have one valence electron and will lose it in order to gain a full octet. There will be an unbalance of electrons and protons where there are more protons there electrons. The correct ion formula for sodium is Na (1+).
Nitrogen has 5 valence electrons and will gain three more to gain a full octet. There will be an unbalance where there are more electrons then protons. Nitrogen will form the ion N (3-).
Calcium has two valence electrons and will lose them in order to gain a full octet. There will be an unbalance where there are more protons then electrons. Calcium will form the ion Ca 2+
Therefore, Ca2+ is the ion with the correct charge.