B. Cooling and freezing of water kills the bacteria present in it
C. With increasing boiler operating pressure of steam, the maximum allowable concentration of
silica in feed water goes on decreasing
D. Dissolved oxygen content in high pressure boiler feed water should be nil
Related Mcqs:
- Deaeration of high pressure boiler feed water is done to reduce ___________________?
A. Foaming from boilers
B. Its dissolved oxygen content
C. Its silica content
D. Caustic embrittlement - Presence of nitrogen in high concentration in contaminated air reduces partial pressure of oxygen in lungs, thereby causing asphyxia (suffocation) leading to death from oxygen deficiency. Concentration of N2 in contaminated air at which it acts as a natural asphyxiate is ≥ _____________ percent?
A. 84
B. 88
C. 80
D. 92 - Soluble silica present in boiler feed water can be removed by______________________?
A. Coagulation
B. Filtration
C. Anion exchanger
D. Preheating it - Foaming and priming in boiler operation can be reduced by reduction in ______________ in feed water?
A. Turbidity
B. Color (Hazen)
C. Total solids
D. All A., B. & C. - Fluorosis (a bone disease) is caused by the presence of high concentration of ____________ in atmospheric air?
A. Hydrocarbons
B. Hydrogen fluoride
C. Hydrogen sulphides
D. Nitrogen dioxide - Pick out the wrong statement ?
A. The concentric layer in atmosphere which contains about 70% of the total mass of atmosphere
and characterised by a steady decrease in temperature is called stratosphere
B. Stratosphere is rich in ozone and is located just above the troposphere
C. Troposphere is a turbulent dusty zone containing much of water vapor and clouds
D. The earth’s atmosphere is an envelope of gases extending upto a height of about 200 kms - Pick out the wrong statement pertaining to ‘green house’ for the plants ?
A. ‘Green house’ (made of glass) allows visible sunlight (i.e., short wavelength solar radiation
like ultra-violet rays) to pass through the glass and heat up the soil thereby warming up plants
inside it
B. The emitted longer wavelength radiation (e.g., infrared) is partly reflected and partly absorbed
by the glass of the green house
C. ‘Green house effect’ in earth’s atmosphere is due to increasing CO2 level in atmosphere, where
CO2 acts like the glass of ‘green house’ thereby warming up the earth’s surface
D. ‘Green house’ is colder than the outside atmosphere - Moist atmospheric air at high temperature (e.g., in summer) having high concentration of sulphur dioxide causes________________?
A. Fading of dyes on textiles
B. Corrosion, tarnishing & soiling of metals
C. Reduced strength of textiles
D. All A., B. and C. - 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 - Maximum allowable concentration of CO2 in air for safe working is _____________ ppm (parts per million)?
A. 50
B. 1000
C. 2000
D. 5000
