Q. Presence of which among the following salts in water causes “Blue Baby Syndrome”?
Answer: Nitrates
Notes: Nitrates in drinking water can cause "blue baby syndrome", which is a condition where infants have a reduced ability to carry oxygen in the blood (methemoglobinemia). The nitrates interfere with the oxygen carrying capacity of hemoglobin. This causes the skin to appear blue or purple. Nitrates in drinking water, often from agricultural runoff, are the cause of "blue baby syndrome".