Which of the following do not cause hardness of water ?: (A) Calcium carbonate, (B) Calcium sulphate, (C) Calcium bicarbonate, (D) Magnesium bicarbonate
Answer is A. * Temporary hardness is a type of water hardness caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). * Permanent hardness is caused by dissolved calcium sulfate (which is not removed by boiling ref : park 21st ed