Limit of BOD prescribed by Central Pollution Control Board for discharge of industrial and municipalwaste waters into natural surface waters is
1. < 3.0 ppm
2. < 10 ppm
3. < 30 ppm
4. < 100 ppm

A water body has low DO content. An organism that is likely to flourish here will be:
1. Gonyaulax, an annelid
2. Gonyaulax, a nematode
3. Tubifex, an annelid
4. Tubifex, a nematode

In which one of the following the BOD (Biochemical oxygen demand) of sewage (s), distellary effluent(DE), paper mill effluent (PE) and sugarmill effluent (SE) have been arranged in ascending order.
1. SE < PE < S < DE
2. PE < S < SE < DE
3. S < DE < PE < SE
4. SE < S < PE < DE

A painful bone condition is produced when the drinking water is contaminated with:
1. Lead
2. Mercury
3. Cadmium
4. Arsenic

Which is not a bio indicator of water pollution
1. Blood worms
2. Stone flies
3. Sewage fungus
4. Sludge worms.

Which one of the following is not used for disinfection of drinking water?
1. Chlorine
2. Ozone
3. Chloramine
4. Phenyl

Biochemical Oxygen Demand (BOD) may not be good index for pollution for water bodies receiving effluents from
1. sugar industry
2. domestic sewage
3. dairy industry
4. petroleum industry

Drinking mineral water with low levels ( ~ 0.02 ppm) of pesticide for long period would
1. Cause cancer of intestine
2. Pesticide accumulation in the body
3. Cause leukaemia
4. Produce immunity against mosquito

Which is correct
1. Both Azotobacter and Rhizobium fix atmospheric nitrogen in root nodules of plants
2. Cyanobacteria, Anabaena and Nostoc are mobilizers of phosphates and plant nutrition in soil
3. At present it is not possible to grow maize without chemical fertilizers
4. excessive use of chemical fertilizers may lead to eutrophication of nearby water bodies

Which one of the following statements pertaining to pollutant is correct?
1. DDT is nonbiodegradable pollutant
2. Excess fluoride in drinking water causes osteoporosis
3. Excess cadmium in drinking water may cause black foot disease
4. Methyl mercury in water may cause ‘’itaiitai’’ disease.