Introduction

Matter around us exists in three physical sates viz. solids, liquids and gases. Each physical state has its characteristic properties. For example, solids are compact, easily transportable, occupy less space but they are rigid, not compressible have high melting points and density. Liquids are easily absorbed, assimilated but they are fluids and occupy slightly more volume. Gases are easy to compress and combust but not easy to transport and store. Thus during their use, substances in each physical state offer some advantages and some disadvantages. In the foregoing discussion, we shall talk more about liquid state of matter.

In everyday life, we come across many substances which are used in liquid state. The water that we drink, the beverages, cold drinks, health drinks, milk, juice, buttermilk we take are some examples of food items taken in liquid form. Perfumes, essences, lotions, air-purifiers, beauty aids, preservatives are some other examples of substances which are used in liquid form. Liquid soaps, detergents, disinfectants, pesticides, medicines are also used in liquid form. These substances are used in liquid form because liquids have an advantage over solids that they are easily absorbed, assimilated, operated, applied and used.