A dissolved substance is a solute that is completely soluble in the solvent, resulting in the formation of a homogeneous solution. The solute can be a solid or a liquid or a gas.
Polar solvents like water dissolve ionic or polar compounds more easily than the non-polar compounds. Ionic compounds or substances that divide into charged ions when mixed with water tend to dissolve completely in water. The substances constituting ions, which are attracted more towards each other, are less soluble in water. There is a chemical rule that like dissolves like. So, the dissolved substance will have the same properties as that of the solvent. Hence, it is dissolved in the solvent.