For existence of aquatic life in water, the dissolved oxygen content in it, should not be less than ______________ ppm?

A. 10000
B. 5
C. 500
D. 1000

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?

A. < 1
B. 10-100
C. 100-200
D. 100-1000

Smog is ______________________?

A. Nothing but black smoke
B. A combination of smoke and fog
C. A liquid particle resulting from vapor condensation
D. A solid particle e.g. fly-ash

Noise pollution level in a chemical plant is expressed in __________________?

A. Roentgen
B. Decibel
C. Hertz
D. None of these

Which of the following is not a weightless pollutant ?

A. SPM
B. Thermal pollution
C. Radioactive rays
D. Noise pollution

Noise level in a quiet private business office is about _____________ decibels?

A. 25
B. 50
C. 70
D. 85

Which of the following fine dust removal equipments is the most efficient ?

A. Bag filter
B. Scrubber
C. Electrostatic precipitator
D. Cyclone separator

Maximum permissible concentration (i.e. TLV) of DDT in public water supply system is _______________ micro gram (μ g)/litre?

A. 22
B. 42
C. 332
D. 1050

From pollution control point of view, the maximum permissible concentration of sulphur dioxide in atmospheric air is about ________________ ppm?

A. 5
B. 50
C. 500
D. 5000

Fresh sewage is ______________ in nature?

A. Acidic
B. Neutral
C. Alkaline
D. Highly acidic