water is a kind of substance & sugar is a kind of pure substance & sugar dissolves in water when they are combined ->  sugar dissolving in water is an example of one substance dissolving in another substance  sugar dissolving in water is an example of one substance dissolving in another substance & a solution is formed by one substance being dissolved in another substance ->  sugar will form a solution when it dissolves in water  sugar will form a solution when it dissolves in water & when one substance is dissolved in another substance then the molecules of that other substance exist in solution -> sugar molecules exist in solution when it forms solution with water