The simple principle for solute dissolution in a particular solvent is "like dissolves like". In the case of water, a solute will dissolve if it is polar. This is because water is a polar solvent. A polar substance is one which has particles that have a net charge on them. This net charge produces forces of attraction. When a polar solute is added to water, the water molecules are attracted to the solute particles and they attach to them. After attaching to the water molecules, the solute particles are dispersed throughout the water. Therefore, the answer is molecules or ions of a solute spread throughout the water molecules.
