Which of the following form solid solutions? Select all that apply.

naturally occurring minerals

gases present in air

HCl and water

sugar and water

metal alloys

I believe the answer is

naturally occurring minerals

metal alloys

The metal alloy is a solid solution that made of metal and other elements.

The example of an alloy is bronze, which is made of copper mixed with nickel, aluminum, zinc or manganese. Most minerals should form a solid solution too, but not all of them. Gases present in air is not solid at all. A solution of HCl and sugar will not form solid solution either.