According to an estimate a substantial fall in carbon-dioxide and Sulphur dioxide level has been found in Delhi between
(1) 1997-2010
(2) 1997-2005
(3) 1990-1997
(4) 2005-2010
How much amount of impurities are present in waste water which make it unfit for human use?
(1) 0.01%
(2) 0.1%
(3) 0.2%
(4) 2%
The impurities of sewage actually has
(1) Suspended solids
(2) Colloidal material
(3) Dissolved material
(4) All of these
Which of the following is not a part of suspended solids in waste water?
(1) Sand
(2) Silt
(3) Clay
(4) Fecal matter
Which of the following is not a part of colloidal material in waste water?
(1) Fecal Matter
(2) Bacteria
(3) Cloth
(4) Silt and paper fibres
Biodegradable organic matter of domestic sewage is used as a substrate by
(1) Bacteria and Other microbes
(2) Industries
(3) Lichens
(4) All of these
Biochemical oxygen demand is
(1) Directly proportional to Biodegradable organic matter
(2) Inversely proportional to Biodegradable organic matter
(3) Depends on direction of flow
(4) Directly proportional to dissolved oxygen
Higher the biodegradable organic matter in sewage
(1) Higher the dissolved oxygen
(2) Higher the BOD
(3) Lower the number of Bacteria
(4) All of these
Algal bloom is
(1) Presence of large amount of nutrients in water
(2) Excessive growth of free floating or planktonic algae
(3) Distinct color to the water bodies
(4) All of these
Which of the following statements is wrong?
(1) Algal bloom cause deterioration of the water quality and fish mortality
(2) Some bloom forming algae are extremely toxic to human beings and animals
(3) Sewage discharge causes mortality of fish and other aquatic creatures
(4) Beautiful orange colored flowers have caused havoc in India because of their faster growth