Dissolving sugar in water is a chemical reaction because it involves the formation of new substances (sugar molecules and water molecules) with different properties than the original substances.

Oxidation is the process in which a substance loses electrons, resulting in an increase in its oxidation state.

Boiling point is a chemical property because it depends on the intermolecular forces between molecules and their tendency to vaporize.

When an acid and a base react, they form a salt and water. This reaction is known as neutralization.

Methane is a hydrocarbon because it contains only carbon and hydrogen atoms.

Sublimation is the process in which a solid substance changes directly into a gas without passing through the liquid phase.

Polyethylene is a polymer because it is made up of repeating units of the same molecule (ethylene).

Evaporation is the process in which a substance absorbs energy and changes from a liquid to a gas.

Sodium is a metal because it has a shiny appearance, is malleable, and is a good conductor of electricity.

Condensation is the process in which a substance changes from a gas to a liquid.

Oxygen is a non-metal because it is a gas at room temperature, is not shiny, and is a poor conductor of electricity.

Freezing is the process in which a substance changes from a liquid to a solid.

Water is a compound because it is made up of two different elements (hydrogen and oxygen) that are chemically combined.

Melting is the process in which a substance changes from a solid to a liquid.

Salt water is a mixture because it is made up of two different substances (salt and water) that are not chemically combined.