Answer is: D) MgF₂.
Magnesium fluoride is salt, ionic compound.
1) Magnesium (Mg) is metal from 2. group of Periodic table of elements and has low ionisation energy and electronegativity, which means it easily lose valence electons (two valence electrons).
Magnesium has atomic number 12, which means it has 12 protons and 12 electrons. It lost two electrons to form magnesium cation (Mg²⁺) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.
Electron configuration of magnesium ion: ₁₂Mg²⁺ 1s² 2s² 2p⁶.
2) Fluorine (F) is nonmetal with greatest electronegativity, which meand it easily gain electrons.
Fluorine jas atomic number 9, which means it has 9 protons and 9 electrons. It gain one electron to form fluorine anion (F⁻) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.
Electron configuration of fluorine ion: ₉F⁻ 1s² 2s² 2p⁶.