Final answer:
The ionic solid among the options given is MgCl₂, which is made up of magnesium ions and chloride ions, forming an ionic bond between a metal and a nonmetal.
Step-by-step explanation:
The question asks to identify which substance is an ionic solid. An ionic solid is formed from the electrostatic attraction between oppositely charged ions, typically consisting of a metal cation and a nonmetal anion. Given the options:
- MgCl₂ - Magnesium chloride is composed of magnesium ions (Mg²⁺) and chloride ions (Cl⁻). Since magnesium is a metal and chlorine is a nonmetal, this combination forms an ionic compound.
- Au - Gold is a metal and would exist as a metallic solid.
- SiO₂ - Silicon dioxide, also known as quartz, is a network of covalently bonded silicon and oxygen atoms and forms a covalent network solid.
- graphite - Graphite consists of layers of carbon atoms bonded together in sheets with covalent bonds, thus forming a covalent network solid.
- sucrose (C₁₂H₂₂O₁₁) - Sucrose is a molecular compound composed of carbon, hydrogen, and oxygen atoms, and in the solid state, it would form molecular crystals.
Therefore, the ionic solid among the options provided is MgCl₂.