Depending upon the physical states of the solute and the solvent, the solutions can be classified into the following types:

Out of these nine types of solutions, three solutions, namely solid in liquid, liquid in liquid, and gas in liquid are very common. In all these three types of solutions, liquid acts as a solvent.

The solutions in which water is the solvent are called aqueous solutions while those in which the solvent is other than water are called non-aqueous solutions. The common non-aqueous solvents are ether, benzene, carbon tetrachloride, etc.

Which of the following is not a solid solution?

Aerated drinks

The answer is 4. Aerated drinks.

Aerated drinks are not solid solutions. They are solutions of carbon dioxide in water. The carbon dioxide is dissolved in the water as gas bubbles. Solid solutions are solutions of two or more solids that are mixed together on a molecular level.

The other options are all solid solutions. Brass is an alloy of copper and zinc. Bronze is an alloy of copper and tin. Hydrated salts are salts that have water molecules incorporated into their crystal structure.

Therefore, the only option that is not a solid solution is aerated drinks.