Write the expression for relative lowering of vapour pressure

The mathematical expression for relative lowering of vapour pressure is _____

The relative lowering in vapour pressure is:

Unit of lowering of vapour pressure is

The law of relative lowering of vapour pressure was given by

Equal mass of a soute are dissolved in equal mass of two solvents A and B and formed very dilute solution. The relative lowering of vapour pressure for the solution B has twice the relative lowering of vapour pressure for the solution A. If m_(A) "and" M_(B) are the molecules mass of solventds A and B respectively, then :