* Compound: A substance formed when two or more different elements are chemically bonded together. Sodium chloride is formed by the chemical bonding of sodium (Na) and chlorine (Cl) atoms.

* Element: A pure substance made up of only one type of atom. Sodium and chlorine are elements.

* Mixture: A combination of two or more substances that are not chemically bonded. While salt can be mixed with other substances, the salt itself is a pure compound.

* Solution: A homogeneous mixture where one substance (solute) is dissolved into another (solvent). Salt dissolves in water to form a solution, but the salt itself is still a compound.

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