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.

What is pumice stone an example of?

Solid foam

The answer is 4. Solid foam.

Pumice stone is a type of solid foam, which is a material that is made up of a gas dispersed in a solid. In the case of pumice stone, the gas is air and the solid is a type of volcanic rock. Pumice stone is lightweight and porous, which makes it a good abrasive. It is often used for cleaning, polishing, and exfoliating.

The other options are not correct. A solid aerosol is a type of colloid, which is a mixture of two or more phases that are not evenly distributed. An emulsion is a type of colloid that is made up of two immiscible liquids, such as oil and water. A liquid aerosol is a type of colloid that is made up of a liquid dispersed in a gas.

Therefore, pumice stone is an example of a solid foam.