Final answer:
The correct formula for the compound formed by magnesium and nitrogen is Mg₃N₂, which is magnesium nitride.
Step-by-step explanation:
The correct formula for the compound made of magnesium and nitrogen is Mg₃N₂. When magnesium and nitrogen react to form an ionic compound, magnesium forms a magnesium ion with a charge of 2+ (Mg2+), losing two electrons to achieve the electron configuration of neon. Nitrogen, being a non-metal in group 15 of the periodic table, gains three electrons to form an anion with a charge of 3- (N3-), called a nitride ion. To achieve electrical neutrality, three magnesium ions will be needed for every two nitride ions, resulting in the formula Mg3N2 for magnesium nitride. This corresponds to option b) Mg₃N₂ in the given choices.