CBSE Class 12-science Answered

The proportionality constant K_f depends on the nature of the solvent is known as Freezing point depression or Cryoscopic constant.

In thermodynamics, the cryoscopic constant, K_f, allows one to relate molality to freezing point depression. It is the ratio of the latter to the former:

Parts per million is the unit where the hardness of water is checked. Its the units in 1 million parts of water.This is a way of expressing very dilute concentrations of substances. Just as per cent means out of a hundred, so parts per million or ppm means out of a million. Usually describes the concentration of something in water or soil. One ppm is equivalent to 1 milligram of something per liter of water (mg/l) or 1 milligram of something per kilogram soil (mg/kg).