Noise level inside a jet airliner in normal flight is about ______________ decibels?

A. 80
B. 100
C. 125
D. 150

Aerosols present in atmospheric air may be__________________?

A. Positively charged
B. Negatively charged
C. Neutral
D. Combination of all A., B. & C.

A considerable part of the harmful ultraviolet radiation of the sum does not reach the earth surface, because of the fact that, there is a layer of _____________ high above earth’s atmosphere, which absorbs it?

A. Hydrogen
B. Carbon dioxide
C. Ozone
D. None of these

Presence of carbon monoxide in atmosphere produced by decomposition of chlorophyll and haemoglobin breakdown of some animals, beyond TLV (>50 ppm) ?

A. Acts as a green house gas thereby raising earth’s temperature
B. Causes asphyxia
C. Causes increase in sea level
D. Enhances the green house effect

Fluorosis is caused due to the presence of excessive amount of ______________ in drinking water?

A. Mercury
B. Lead
C. Fluoride
D. Arsenic

Soluble silica present in boiler feed water can be removed by______________________?

A. Coagulation
B. Filtration
C. Anion exchanger
D. Preheating it

Which of the following gases is having the widest explosion limit (about 2 to 81% gas in gasair mixture), rendering it the property of the most explosive gas ?

A. Hydrogen
B. Acetylene
C. Carbon monoxide
D. Ammonia

Maximum permissible limit of mercury in human blood is ______________ micrograms/100 c.c?

A. 1
B. 7
C. 19
D. 82

Brown spots in fabrics will be caused by washing with water containing large amount of___________________?

A. Iron
B. Zinc
C. Iodine
D. Bromine

The main type of sludge gas evolved during sewage treatment in Imhoff tank is___________________?

A. CO2
B. CH4
C. CO
D. H2