Q. Which of the following salts are the main causes of temporary hardness? Calcium sulphate Magnesium sulphate Magnesium chloride Magnesium carbonate Answer: Magnesium carbonate.

Q. In most freshwater lakes, the algal productivity is limited by the availability of which of the following inorganic ions? Carbon Nitrogen Phosphorus All of the above Answer: Phosphorus.

Q. Which of the following techniques is used to determine the concentration of odour compounds in the given water sample? Settling Flushing Stripping Chlorination Answer: Stripping.

Q. Which of the following is a waterborne disease? Typhoid Cholera Diarrhoea All of the above Answer: All of the above

Q. What is the health effects of excess fluoride in drinking water? Fluorosis Toothaches Lung disease Intestinal infection Answer: Fluorosis.

Q. Which of the following techniques is used to remove fluorides from the water bodies? Osmosis Ion exchange Lime softening Both 2 and 3 Answer: Both 2 and 3

Q. Which of the following is mainly responsible for the causes of water pollution? Afforestation Oil refineries Paper factories Both 2 and 3 Answer: Both 2 and 3

Q. Chlorofluorocarbon are nonflammable chemicals mainly used in _________. Perfumes Refrigerators Air conditioners All of the above Answer: All of the above.

Q. Which of the following salts is the main cause of permanent hardness of water? Magnesium sulphate Magnesium bicarbonate Magnesium carbonate None of the above Answer: Magnesium sulphate.

Q. Which of the following techniques is used for reducing the total dissolved solids (TDS) in the water? Osmosis Ion exchange Distillation Both 2 and 3 Answer: Both 2 and 3.