Which term describes salt water, vinegar, bronze, air, beach sand?

The correct answer is mixtures.

Salt water, vinegar, bronze, air, and beach sand are all mixtures, some of them more homogeneous or heterogeneous than others. A mixture, as the name itself says, is a blend of more than one element. So salt water is a mixture of salt and water, vinegar is a mixture of acetic acid and water, bronze is a mixture of copper and other metals, air is a mixture of nitrogen, oxygen, and other elements, and beach sand is a mixture of sand and water.