This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
Hardness of water is contributed by following salts except - 
Select and explain. 
A. Calcium gluconate, B. Magnesium chloride, C. Calcium sulfate, D. Magnisium bicarbonate
A: Calcium gluconate
Answer: A: Calcium gluconate 
Explanation: The hardness of water is caused mainly by four dissolved compounds.These are Calcium bicarbonate Magnesium bicarbonate Calcium sulphate Magnesium sulphate Presence of any of these salt produces hardness (refer pgno:727 park 23rd edition)