What are solids that dissolve in liquid?

Answer 1

Kind of a vague question, but perhaps you mean what are solutes? A solute is a substance, often a solid, which dissolves in a solvent, often a liquid. This leads to a discussion about polar and non-polar solutes and solvents. Generally speaking, polar solutes dissolve in polar solvents and non-polar solutes dissolve in non-polar solvents. This is the chemical principle of "like dissolves like." Polarity is determined by unshared electrons causing partial charge differences across a molecule.