1. Ambient noise level can be reduced by __________ decibels by planting trees (like coconut, neem etc.) near public utility buildings (like hospitals & schools)
2. A shallow pond in which the sewage is retained and biologically treated is called
3. The amount of chemical coagulant added for treatment of polluted water __________ with increase in temperature of the polluted water to be treated
4. Presence of bacteria in potable (drinking) water causes
5. Atmospheric pollution caused by the exhaust gas of supresonic transport air-crafts is mostly in the atmospheric region called
6. Iron & manganese present in the polluted water is removed by
7. Maximum permissible turbidity in potable water is __________ ppm
8. 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
9. Which is the most practical and economical method for removal of suspended solid matter from polluted water ?
10. Pick out the wrong statement
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