651. The main pollutant of leather tanneries in the waste water is____________________?
A. chromium III
B. chromium IV
C. chromium V
D. chromium VI

652. Which substance can be used for disinfecting water ?
A. KMnO4
B. Alums
C. Ozone
D. All

653. Which one of the following makes the bulk of hydrospheres content ?
A. oceans
B. glaciers & icecaps
C. fresh water lakes and ponds
D. All have equal distribution

654. The percentage of suspended solid waste in raw water is removed by coagulation is__________________?
A. 60
B. 70
C. 80
D. 90

655. The main product of bacterial action is_________________?
A. Nox
B. NO2
C. N2O3
D. NO

656. Pollutants have adverse effect over_________________?
A. Biosphere
B. Ecosystem
C. Both a & b
D. Hydrosphere

657. Which of the following is not a heavy industry ?
A. iron
B. fertilizer
C. paper
D. none

658. Requirement of macronutrient per acre of the land is_________________?
A. 5 to 200 kg
B. 20-200 kg
C. 200-400 kg
D. 30-400 kg

659. Which of the following is not a secondary pollutant_________________?
A. ozone
B. carbonic acid
C. sulphuric acid
D. carbon dioxide

660. Major cause of SO2 on global scale is__________________?
A. volcanoes
B. electric sparks
C. combustion
D. all