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
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
Out of the following, TLV of _______________ is maximum (about 500 ppm)?
(A) Carbon dioxide
(B) Toluene
(C) Carbon disulphide
(D) Acetaldehyde
Fine grit present in sewage is removed in the _____________ during sewage treatment?
(A) Grit chamber
(B) Detritus tank
(C) Trickling filter
(D) Skimming tank
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
(D) All
Most efficient and suitable dust removal equipment for removal of fly-ash from flue gas in a thermal power plant is the__________________?
(A) Gravity settling chamber
(B) Cyclone separator
(C) Electrostatic precipitator
(D) Bag filter
White smoke coming out of the chimney of a furnace indicates the use of_________________?
(A) Low excess air
(B) Very high excess air
(C) Gaseous fuel in the furnace
(D) Liquid fuel in the furnace
Carbonaceous particles having size less than 1 μm are called___________________?
(A) Grit
(B) Aggregates
(C) Aerosols
(D) Smoke
Methyl isocyanate (MIC) gas (TLV <1 ppm), which caused Bhopal gas tragedy in 1984 falls under the category of ______________ toxic gas?
(A) Moderately
(B) Highly
(C) Extremely
(D) Very extremely
Beyond what concentration of H2S in air, acute danger to human life exists ?
(A) 50 ppm
(B) 100 ppm
(C) 300 ppm
(D) 700 ppm