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.

Stone flies are not bioindicators. Bioindicators provide a range of techniques to assess the impacts of air pollution from reactive nitrogen (N) compounds on statutory nature conservation sites. They complement physical monitoring of atmospheric concentrations and deposition and risk assessment based on the critical loads approach by providing site-based information on atmospheric N concentrations, N deposition and/or ecological impacts.

Correct Option: B

Stone flies are not bioindicators. Bioindicators provide a range of techniques to assess the impacts of air pollution from reactive nitrogen (N) compounds on statutory nature conservation sites. They complement physical monitoring of atmospheric concentrations and deposition and risk assessment based on the critical loads approach by providing site-based information on atmospheric N concentrations, N deposition and/or ecological impacts.

More value of BOD means the water sample is polluted by organic matter. BOD of distillary effluent is 40000 mg/L and that of paper mill effluent and sewage is 190 mg/L and 30 mg/L respectively.

Correct Option: B

More value of BOD means the water sample is polluted by organic matter. BOD of distillary effluent is 40000 mg/L and that of paper mill effluent and sewage is 190 mg/L and 30 mg/L respectively.

Lots of urea and phosphate fertilizer were used in the crops in the vicinity and the lake water turned green and stinky. Due to this, lake near a village suffered heavy mortality of fishes within a few days.

Correct Option: C

Lots of urea and phosphate fertilizer were used in the crops in the vicinity and the lake water turned green and stinky. Due to this, lake near a village suffered heavy mortality of fishes within a few days.

DDT residues are rapidly passed through food chain causing biomagnification because DDT is lipo soluble. Biomagnification, also known as bioamplification or biological magnification, is the increase in concentration of a substance, such as the pesticide DDT, that occurs in a food chain as a consequence of:
• Persistence (slow to be broken down by environmental processes).
• Food chain energetics.
• Low (or non-existent) rate of internal degradation/excretion of the substance (often due to water-insolubility).

Correct Option: D

DDT residues are rapidly passed through food chain causing biomagnification because DDT is lipo soluble. Biomagnification, also known as bioamplification or biological magnification, is the increase in concentration of a substance, such as the pesticide DDT, that occurs in a food chain as a consequence of:
• Persistence (slow to be broken down by environmental processes).
• Food chain energetics.
• Low (or non-existent) rate of internal degradation/excretion of the substance (often due to water-insolubility).