201. Maximum permissible residual chlorine in treated water should be __________ mg/litre.
202. Which of the following is the most active zone of atmosphere in which weathering events like rain, storm & lightning occur ?
203. Which is the most widely used coagulant for the treatment of turbid water ?
204. Which of the following is not a natural source of air pollution ?
205. 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.
206. Photochemical smog is formed from automobile exhaust
207. Reinglemann chart is used for the measurement of the
208. Disinfection of water is done to remove
209. Which of the following fine dust removal equipments is the most efficient ?
210. Which of the following industries discharge mercury as a pollutant ?
211. Threshold limit value (TLV) of CO in air is __________ ppm.
212. Lead exhausted in the atmosphere by automobiles using leaded petrol (i.e. tetraethyl lead for improving octane number) is a lethal air pollutant which causes
213. Oilish impurities present the effluent discharged from the electroplating industry is normally not removed by
214. In large thermal power stations very fine particulates present in flue gas are removed by
215. Threshold limit value (TLV) means maximum permissible/acceptable concentration. TLV of phosgene in air is about __________ ppm (parts per million).
216. The density of the gases (present in air) decreases with increasing altitude to such an extent, that about 70% of the mass of atmospheric air is found in the lower 5 km. of the atmosphere. This lower region of atmosphere is called the
217. Biological oxidation ponds remove organic matters present in the polluted water by
218. Which of the following is an adsorbant for removal of nitrogen oxides from gas/air ?
219. Out of the following, TLV of __________ is the minimum (about 0.02 ppm).
220. The average thickness of ozone layer in stratosphere is about __________ dobson unit (DU).
221. Polyvinyl chloride containers are not suitable for storing
222. Presence of nitrogen in high concentration in contaminated air reduces partial pressure of oxygen in lungs, thereby causing asphyxia (suffocation) leading to death from oxygen deficiency. Concentration of N2 in contaminated air at which it acts as a natural asphyxant is ≥ __________ percent.
223. TLV of ammonia, nitrogen dioxide and phenol vapor in air is __________ ppm.
224. Corrosion in boilers can be prevented by
225. Water filtration rate in a slow sand filter ranges from __________ litres/m2/hr.