Addition of a non-volatile solute to a solvent always increases the colligative property such as π,ΔPP∘,ΔTb
. All these colligative properties are directly proportional to the molality. The increase in colligative properties is due to increase in number of solute particles. If relative decrease in vapour pressure is 0.4 for a solution containing 1 mole NaCl in 3 moles of H2O, then what is the percentage ionization of NaCl?