This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
1 meq/ L of hardness of water is equivalent to presence of: 
Select and explain. 
A. 25 mg calcium bicarbonate in 1 litre of water, B. 50 mg calcium bicarbonate in 1 litre of water, C. 100 mg calcium bicarbonate in 1 litre of water, D. 150 mg calcium bicarbonate in 1 litre of water
B: 50 mg calcium bicarbonate in 1 litre of water
Answer: B: 50 mg calcium bicarbonate in 1 litre of water 
Explanation: Hardness of water is expressed in meq/L. 1 meq/L of hardness producing ion is equal to 5o mg of calcium bicarbonate in 1 litre of water. Ref: Park 21st edition page: 671.