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.Management Sciences
Category: Chemical Environmental Engineering
A gas is termed as non-toxic, if its maximum permissible concentration (TLV) ranges from ______________ ppm?
0
A. 1000 to 2000
B. 3000 to 6000
C. 6000 to 9000
D. 10000 to 100000
Noise level during normal conversation among men is about ______________ decibels?
A. 10
B. 45
C. 90
D. 115
Tri-sodium phosphate is used in boiler water treatment to reduce____________________?
A. Turbidity
B. Caustic embrittlement
C. Suspended silica
D. Dissolved oxygen
On prolonged exposure to high concentration of carbon monoxide (> 5000 ppm), man dies because __________________?
A. Of clotting of blood
B. Of jamming of respiratory tract
C. It forms carboxyhemoglobin by combining with haemoglobin of blood, thereby making it
incapable of absorbing oxygen
D. It forms CO2 by combining with oxygen present in the blood
The main type of sludge gas evolved during sewage treatment in Imhoff tank is___________________?
A. CO2
B. CH4
C. CO
D. H2
Which of the following is a secondary air pollutant ?
A. Photochemical smog
B. Sulphur dioxide
C. Nitrogen dioxide
D. Dust particles
The main pollutant in waste water discharged from a petroleum refinery is oil (both in free and emulsified form). Free oil is removed by_________________?
A. Biological oxygen pond
B. Aerated lagoons
C. Trickling filters
D. Gravity separator having oil skimming devices
Which of the following is the most detrimental for water used in high pressure boiler ?
A. Silica
B. Turbidity
C. Phenol
D. Dissolved oxygen
The most commonly used chemical coagulant in water treatment is________________?
A. Ferrous sulphate
B. Alum
C. Lime
D. Hydrazine
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