Question

as generally there are two parameter for estimating the compressible nature of fluids - bulk modulus and compressibility which are reciprocal of each other , which one is used where, when and with what things

Answer 1

The compressibility factor is also often confused with its reciprocal, the bulk modulus, which has the unit of a pressure. This confusion is rather common in the case of liquids.

It's the modulus that increases with pressure, or rather with density, because molecules add their volume to the vacuum volume (perfect gas) occupied by the thermal movements, and molecules are stiffer.

http://www.chemicalforums.com/index.php?topic=46463.0

Answer 2

@jeanetteBaker : actually i wanted to know that when we use bulk modulus and compressibility as parameter for comparing the relative compressible nature of fluid i.e for example may be for liquids we generally use bulk modulus and for gases generally we use compressibility like that
thank u for ur reply