because perfume is a volatile substance and when it is prayed the moment it becomes vapours. The particles of perfume have good tendency to intermix
with particles(diffusion) of air can travel several metres
although citric acid is mostly produced from starch or sucrose based media using liquid fermentation, a variety of raw materials such as molasses, several starchy materials and hydrocarbons have also been employed. both, cane and beet molasses are suitable for citric acid production.
the process by pure solid is separated from solution in the form of its crystals is called crystallization.
crystallization is better than evaporation because some solids can decompose or can get burned during evaporation.
also in some cases impurities can remain dissolved in the solution evaporation cannot be removed even after filtration.