Magnesium oxide MgO is an ionic inorganic solid. This can be justified based on the following reasons:1. Formation: Magnesium oxide is formed by the reaction between a metal magnesium and a non-metal oxygen . Magnesium loses two electrons to form a Mg2+ cation, and oxygen gains two electrons to form an O2- anion. The electrostatic attraction between these oppositely charged ions results in the formation of an ionic compound, MgO.2. Crystal structure: Magnesium oxide has a crystalline structure, specifically a face-centered cubic FCC lattice, where Mg2+ and O2- ions are arranged in a regular, repeating pattern. This is a characteristic feature of ionic solids.3. Physical properties: Ionic solids like magnesium oxide exhibit high melting and boiling points due to the strong electrostatic forces between the ions in the lattice. MgO has a high melting point of 2852C 5166F and a high boiling point of 3600C 6512F , which supports its classification as an ionic solid.4. Electrical conductivity: Magnesium oxide is a poor conductor of electricity in its solid state, as the ions are held in fixed positions within the lattice and cannot move freely. However, when molten or dissolved in water, MgO conducts electricity due to the mobility of its ions. This behavior is typical of ionic compounds.In summary, based on its formation, crystal structure, physical properties, and electrical conductivity, magnesium oxide can be classified as an ionic inorganic solid.