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

Q. In filtration, the amount of dissolved solids passing through the filters is Difference between total solids and suspended solidsSum of total solids and suspended solidsIndependent of suspended solidsNone of the above Answer: Difference between total solids and suspended solids

Q. Step of sewage water treatment in which there is some aeration and organic material is converted to inorganic materials is called Primary sewage treatmentSecondary sewage treatmentActivated sludge treatmentChlorination Answer: Secondary sewage treatment

Q. What is second step of raw water treatment? SedimentationCoagulationFiltrationChlorination Answer: Coagulation

Q. What is first step of raw water treatment? ChlorinationFiltrationCoagulationSedimentation Answer: Sedimentation