100 mL of water at room temperature of 25°C is taken in a beaker and little of solid S is dissolved in it by stirring to obtain a solution X. More and more of solid S is added to the solution with constant stirring. While keeping the temperature of solution constant at 25°C . After some time it is observed that no more  solid dissolves in water and at the same time some solid is also left un dissolved at the bottom of the beaker. The contents of beaker are filtered through a filter paper to obtain solution Y in the form of a filtrate.
i) X is unsaturated solution 
ii) Y is a saturated solution
iii) If we cool the filtrate to 20°C  some amount of solid ‘S’ is precipitated out 
iv) The solubility of solid ‘S’ increases with decrease in temperature