Q. Chlorofluorocarbon are nonflammable chemicals mainly used in _________. PerfumesRefrigeratorsAir conditionersAll of the above Answer: All of the above.

Q. Which of the following salts is the main cause of permanent hardness of water? Magnesium sulphateMagnesium bicarbonateMagnesium carbonateNone of the above Answer: Magnesium sulphate.

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

Q. Which of the following statements are true about CNG -Compressed natural gas? It is a clean fuelIt is a harmful fuelIt is a polluting fuelAll of the above Answer: It is a clean fuel.

Q. Which of the following rivers is called the world’s most polluted river? Ganga RiverChenab RiverCauvery RiverYamuna River Answer: Ganga River.

Q. Which of the following are the primary causes of water pollution? PlantsAnimalsHuman activitiesNone of these Answer: Human activities.

Q. The following cause alkalinity as well hardness in natural water. Calcium carbonateCalcium bicarbonateMagnesium carbonateAll of the above Answer: All of the above

Q. Step of sewage water treatment in which sewage is placed in tanks and aerated with large blowers is called Activated sludge treatmentChlorinationSecondary sewage treatmentPrimary sewage treatment Answer: Activated sludge treatment

Q. What is fourth step of raw water treatment? SedimentationCoagulationChlorinationFiltration Answer: Chlorination

Q. The Total dissolved solids (TDS) can be reduced by the following method DistillationReverse osmosisIon exchangeAll of the above Answer: All of the above