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211.The type of bacteria which is active in trickling filter during biological treatment of sewage is the _________ bacteria.
212.The upper layer of atmosphere is called the
213.The weakest sound that can be heard by a person in a quiet environment is equivalent to _________ decibel.
214.The widest explosive limit is of _________ , thereby making it the most explosive gas.
215.There are five concentric layers within the atmosphere which is differentiated on the basis of temperature. The atmospheric layer which lies close to the earth's surface in which human being along with other organisms live is called troposphere. The rate at which air temperature in the troposphere gradually decreases with height is about _________ °C/km.
216.There are thirteen metals which are treated as pollutants. Which of the following metals is not a pollutant?
217.Thermal pollution due to excessive heat&temperature in the working place causes
218.Thermal pollution of water increases its toxicity and oxidation of oxygen demanding waste besides favouring bacterial growth. A rise in water temperature by 10°C, doubles the toxic effects of _________ present in it.
219.Threshold limit value (TLV) i.e., the maximum permissible safe limit of phosgene gas which Hitler used to use to kill his enemies in 'gas chamber' is about _________ ppm.
220.Threshold limit value (TLV) means maximum permissible/acceptable concentration. TLV of phosgene in air is about _________ ppm (parts per million).