The pH value of potable water should be between____________________?

A. 1 to 1.5
B. 6.5 to 8
C. 13 to 14
D. 4 to 5

Which of the following causes death by asphyxiation, if its presence in atmospheric air exceeds maximum allowable concentration (i.e. > 50 ppm) ?

A. Benzopyrene
B. Peroxyacetyl nitrate
C. Carbon monoxide
D. Sulphur dioxide

Sulphur dioxide present in the industrial chimney exhaust gases causes____________________?

A. Respiratory & lung disease
B. Reduction in plant’s productivity owing to acid rain
C. Corrosion of building materials
D. All A., B. and C.

Corrosion in boilers can be prevented by _________________?

A. Deaeration of feed water
B. Enhancing pH of feed water by adding alkali
C. Feeding sodium sulphite or hydrazine phosphate to the boilers, which combines with oxygen
and prevents corrosion

Fine grit present in sewage is removed in the _____________ during sewage treatment?

A. Grit chamber
B. Detritus tank
C. Trickling filter
D. Skimming tank

Out of the following, TLV of _______________ is maximum (about 500 ppm)?

A. Carbon dioxide
B. Toluene
C. Carbon disulphide
D. Acetaldehyde

Threshold limit value (TLV) means maximum permissible/acceptable concentration. TLV of phosgene in air is about ______________ ppm (parts per million)?

A. 0.002
B. 0.2
C. 1.2
D. 4.8

As per the world health organisation (WHO) specification, the maximum permissible concentration (i.e., TLV) of particulate matter in air is _____________ μg/m3.(μg-microgram)?

A. 10
B. 90
C. 800
D. 750

Presence of _____________ bacteria in water causes disease like typhoid?

A. Aerobic
B. Pathogenic
C. Anaerobic
D. Non-pathogenic

In large thermal power stations very fine particulates present in flue gas are removed by___________________?

A. Wet scrubber
B. Bag filter
C. Electrostatic precipitators
D. Dust catcher