Which of the following do not cause hardness of water?
Ans. a. Calcium carbonateRef: Parks Text book of Preventive and Social Medicine, 24th Ed; Page No-763Hardness is defined as soap destroying power of water.Hardness is mainly due to 4 dissolved compounds:Calcium bicarbonateCalcium sulfateMagnesium bicarbonateMagnesium sulfateOther compounds responsible for hardness are chlorides and nitrates of calcium and magnesium and iron, manganese, aluminium compounds to a small extent.There are 2 types of hardness:Temporary hardness: Due to carbonates of Ca and MgPermanent hardness: Due to sulphate, chloride and nitrates of Ca and Mg
Calcium carbonate
Calcium sulfate
Calcium bicarbonate
Magnesium bicarbonate
Biostatistics