Properties of Ionic Magnesium Oxide

Steps:

• Identify magnesium oxide (MgO) as an ionic compound formed by electron transfer from Mg to O, creating Mg²⁺ cations and O²⁻ anions.
• Recall ionic compounds have strong electrostatic bonds, leading to high melting points but no conductivity in solid state at room temperature.
• Note that melting frees ions, allowing electrical conductivity in molten form.
• Evaluate each option against these ionic properties.

Why C is correct:

• Ionic compounds conduct electricity when molten as mobile ions carry charge, per the definition of ionic bonding.

Why the others are wrong:

• A: Lacks electrical conductivity at room temperature and pressure as solid ions are fixed in lattice.
• B: Composition is reversed; Mg forms cations (Mg²⁺), O forms anions (O²⁻).
• D: Bonding is ionic via attraction, not covalent sharing of electrons.

Final answer: C