Biochemical Oxygen Demand (BOD) is the amount of oxygen required to destroy the organic waste by the bacteria. The more oxygen required for bacteria that means there is more organic waste. For pure drinking water it is decided less than 1 ppm and for industrial & municipal waste it is less than 10 ppm. In Yamuna water in Delhi it is about 1000 ppm.

Correct Option: A

Biochemical Oxygen Demand (BOD) is the amount of oxygen required to destroy the organic waste by the bacteria. The more oxygen required for bacteria that means there is more organic waste. For pure drinking water it is decided less than 1 ppm and for industrial & municipal waste it is less than 10 ppm. In Yamuna water in Delhi it is about 1000 ppm.

Since all surface and ground water contains salts to varying degrees. Therefore excessive irrigation followed by evaporation of the unabsorbed water leads to salinity. This also leads to waterlogging.

Correct Option: C

Since all surface and ground water contains salts to varying degrees. Therefore excessive irrigation followed by evaporation of the unabsorbed water leads to salinity. This also leads to waterlogging.

Chlorine, ozone, chloramine are used for disinfection of drinking water.

Correct Option: D

Chlorine, ozone, chloramine are used for disinfection of drinking water.

Three fourth surface of earth is covered by oceans which contain 97.5% of total water. It is marine water with about 3.5% salt content only 2.5% is fresh water which occurs on land. Most of this water (1.97%) occurs as frozen ice caps and glaciers, 0.5% fresh water occurs as ground water. Rivers and lakes contain 0.02%, soil 0.01% while atmosphere possesses 0.001% of water as vapours.

Correct Option: A

Three fourth surface of earth is covered by oceans which contain 97.5% of total water. It is marine water with about 3.5% salt content only 2.5% is fresh water which occurs on land. Most of this water (1.97%) occurs as frozen ice caps and glaciers, 0.5% fresh water occurs as ground water. Rivers and lakes contain 0.02%, soil 0.01% while atmosphere possesses 0.001% of water as vapours.

MIC ? (Methyl Isocyanate) was the deadly gas leaked from the fertilizer plant of Union Carbide company in Bhopal.

Correct Option: A

MIC ? (Methyl Isocyanate) was the deadly gas leaked from the fertilizer plant of Union Carbide company in Bhopal.