MCQOPTIONS
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MCQOPTIONS
This section includes 299 Mcqs, each offering curated multiple-choice questions to sharpen your RRB Junior Engineer knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
COD of raw municipal sewage may be in the range of about __________ mg/litre. |
| A. | 1-2 |
| B. | 5-10 |
| C. | 90-120 |
| D. | 1500-2500 |
| Answer» D. 1500-2500 | |
| 102. |
Hazardous/polluting chemical industries should have an 'exclusion zone' with a green belt and general public access prohibited around it, covering a radius of ____ metres. |
| A. | 100 |
| B. | 1000 |
| C. | 400 |
| D. | 4000 |
| Answer» C. 400 | |
| 103. |
Presence of __________ in water stream are deleterious to aquatic life. |
| A. | soluble and toxic organics. |
| B. | suspended solids. |
| C. | heavy metals and cynides. |
| D. | all (a), (b) & (c). |
| Answer» E. | |
| 104. |
The term Biological Oxygen Demand (BOD) is used in relation to |
| A. | potable water |
| B. | cooling water |
| C. | distilled water |
| D. | industrial effluents |
| Answer» E. | |
| 105. |
Noise level audible to audience sitting in the 5th row from the stage during a large orchestra show corresponds to about __________ decibels. |
| A. | 105 |
| B. | 135 |
| C. | 160 |
| D. | 185 |
| Answer» C. 160 | |
| 106. |
Presence of soluble organics in polluted water causes |
| A. | undesirable plants growth. |
| B. | depletion of oxygen. |
| C. | fire hazards. |
| D. | explosion hazards. |
| Answer» C. fire hazards. | |
| 107. |
Carbon monoxide is a pollutant, which causes |
| A. | respiratory disease (e.g. asthma). |
| B. | asphyxiation (suffocation) leading to death. |
| C. | retardation in crop growth. |
| D. | damage to building materials like marble. |
| Answer» C. retardation in crop growth. | |
| 108. |
Pollution by particulate matter emission in the atmosphere does not take place during metal |
| A. | grinding |
| B. | machining |
| C. | cutting |
| D. | polishing |
| Answer» E. | |
| 109. |
Ozone is |
| A. | a primary pollutant. |
| B. | a secondary pollutant. |
| C. | impervious to ultra-violet rays. |
| D. | both (b) and (c) |
| Answer» E. | |
| 110. |
Noise produced by cooling fans (employed in air cooled heat exchangers or cooling tower) is mainly caused due to the turbulence created by blade passage through air. It can be reduced by use of a slower fan |
| A. | with greater number of blades. |
| B. | of increased diameter. |
| C. | both (a) & (b). |
| D. | neither (a) nor (b). |
| Answer» D. neither (a) nor (b). | |
| 111. |
BOD of raw municipal sewage may be in the range of about __________ mg/litre. |
| A. | 1-2 |
| B. | 5-10 |
| C. | 150-300 |
| D. | 2000-3000 |
| Answer» D. 2000-3000 | |
| 112. |
In water treatment, alum[Al₂(SO₄)₃] is used for the process of |
| A. | filtration |
| B. | coagulation |
| C. | sedimentation |
| D. | disinfection |
| Answer» C. sedimentation | |
| 113. |
For existence of aquatic life in water, the dissolved oxygen content in it, should not be less than __________ ppm. |
| A. | 10000 |
| B. | 5 |
| C. | 500 |
| D. | 1000 |
| Answer» C. 500 | |
| 114. |
TLV of NO₂ & NO exposure for the human being is 5 & 25 ppm respectively. Prolonged exposure of human being to NO₂ causes |
| A. | skin disorder |
| B. | bronchitis |
| C. | bone disease |
| D. | cancer |
| Answer» C. bone disease | |
| 115. |
Which of the following air pollutants is not toxic to vegetation i.e., doesn't cause vegetation damage ? |
| A. | Smog & ozone |
| B. | Hydrogen fluoride & nitrogen oxides |
| C. | Sulphur dioxide & spray of weed killers |
| D. | Carbon monoxide |
| Answer» E. | |
| 116. |
The biological decomposition of organic substances in wastes controlled conditions is called |
| A. | incineration |
| B. | biological oxidation |
| C. | composting |
| D. | none of these |
| Answer» D. none of these | |
| 117. |
The function of skimming tank in sewage treatment is to remove __________ substances. |
| A. | dissolved solid |
| B. | suspended solid |
| C. | oil & fatty |
| D. | gritty & inorganic |
| Answer» D. gritty & inorganic | |
| 118. |
Which of the following industries discharge mercury as a pollutant ? |
| A. | Chloro-alkali industry |
| B. | Tanneries |
| C. | Beverage plant |
| D. | Phosphoric acid plant |
| Answer» B. Tanneries | |
| 119. |
Salt content in sea water is about __________ percent. |
| A. | 0.5 |
| B. | 1 |
| C. | 3.5 |
| D. | 10 |
| Answer» D. 10 | |
| 120. |
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. |
| Answer» C. its silica content. | |
| 121. |
Permissible safe limit (TLV) of __________ toxic gas is 100-1000 parts per million (ppm). |
| A. | highly |
| B. | moderately |
| C. | extremely |
| D. | very extremely |
| Answer» C. extremely | |
| 122. |
The permissible color for domestic water supply is __________ ppm. |
| A. | 1 |
| B. | 20 |
| C. | 100 |
| D. | 1000 |
| Answer» C. 100 | |
| 123. |
The principal gas evolved from sludge digestion tank is |
| A. | CO |
| B. | CO₂ |
| C. | CH₄ |
| D. | N₂ |
| Answer» D. N₂ | |
| 124. |
The earth's atmosphere is an envelope of gases present upto a height of about __________ kms. |
| A. | 10 |
| B. | 200 |
| C. | 1000 |
| D. | 2000 |
| Answer» C. 1000 | |
| 125. |
Which of the following pollutants, if present in atmosphere is detectable by its odour ? |
| A. | CO |
| B. | SO₂ |
| C. | NO₂ |
| D. | CO₂ |
| Answer» C. NO₂ | |
| 126. |
Fine grit present in sewage is removed in the __________ during sewage treatment. |
| A. | grit chamber |
| B. | detritus tank |
| C. | trickling filter |
| D. | skimming tank. |
| Answer» C. trickling filter | |
| 127. |
Shouting by a man at his full voice corresponds to a voice level of about __________ decibels. |
| A. | 25 |
| B. | 50 |
| C. | 80 |
| D. | 120 |
| Answer» D. 120 | |
| 128. |
Which of the following is an adsorbant used for the removal of SO₂ from gas/air ? |
| A. | Bog iron |
| B. | Limestone powder or alkalised alumina |
| C. | Silica gel |
| D. | Active carbon |
| Answer» C. Silica gel | |
| 129. |
World environment day is observed every year on the 5th of |
| A. | June |
| B. | December |
| C. | July |
| D. | September |
| Answer» B. December | |
| 130. |
In a sedimentation tank, the detention period for water ranges from __________ hours. |
| A. | 2 to 4 |
| B. | 8 to 12 |
| C. | 16 to 20 |
| D. | 24 to 32 |
| Answer» B. 8 to 12 | |
| 131. |
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 |
| Answer» C. 1.2 | |
| 132. |
The major reason of hydrodynamic noise (i.e., noise resulting from liquid flow) is |
| A. | pipe vibrations. |
| B. | cavitation. |
| C. | boundary layer separation. |
| D. | fluctuation in liquid flow. |
| Answer» C. boundary layer separation. | |
| 133. |
Which of the following is not an air pollutant ? |
| A. | Ozone |
| B. | Carcinogens |
| C. | Pesticides |
| D. | Metallic powders |
| Answer» B. Carcinogens | |
| 134. |
Foul odour and bad taste of water is removed by treating with |
| A. | alum |
| B. | bleaching powder |
| C. | activated carbon |
| D. | copper sulphate. |
| Answer» D. copper sulphate. | |
| 135. |
The weakest sound that can be heard by a person in a quiet environment is equivalent to __________ decibel. |
| A. | 1 |
| B. | 5 |
| C. | 10 |
| D. | 20 |
| Answer» B. 5 | |
| 136. |
Coal mines drainage waste water (acidic in nature) results from the earth's water percolating through the voids created in coal bed during mining. This polluted water which either drains out naturally to water courses or are removed before starting the mining is |
| A. | neutralised by alkali treatment. |
| B. | left as such without any treatment. |
| C. | diluted with fresh water to reduce its acidity. |
| D. | none of these. |
| Answer» B. left as such without any treatment. | |
| 137. |
Oil and grease present in an emulsified state in waste water discharged from industries can be removed by |
| A. | biological oxidation. |
| B. | skimming off. |
| C. | settling out using chemical reagents. |
| D. | chlorination. |
| Answer» D. chlorination. | |
| 138. |
The concentration of water vapour in troposphere, which depends upon the altitude & temperature varies in the range of zero to __________ percent. |
| A. | 1 |
| B. | 4 |
| C. | 8 |
| D. | 12 |
| Answer» C. 8 | |
| 139. |
The common pollutant generated in chlor-alkali industry and battery manufacture is |
| A. | mercury |
| B. | brine |
| C. | phosphate |
| D. | none of these |
| Answer» B. brine | |
| 140. |
Green house gases blanket/block the infrared radiation from earth's surface to the atmosphere leading to its progressive warming up. Which of the following gases does not exhibit green house effect ? |
| A. | CO₂ |
| B. | H₂ |
| C. | SO₃ |
| D. | N₂ |
| Answer» D. N₂ | |
| 141. |
A gas is termed as non-toxic, if its maximum permissible concentration (TLV) ranges from __________ ppm. |
| A. | 1000 to 2000 |
| B. | 3000 to 6000 |
| C. | 6000 to 9000 |
| D. | 10000 to 100000 |
| Answer» E. | |
| 142. |
5-200 μm size particles are called |
| A. | colloids or aerosols |
| B. | powder |
| C. | dust |
| D. | smoke |
| Answer» B. powder | |
| 143. |
'Safe limit' called Threshold Limit Value (TLV) of carbon monoxide in atmospheric air is < 50 ppm. The main source of carbon monoxide pollutant in air is the |
| A. | industrial chimney exhaust. |
| B. | automobiles exhaust. |
| C. | photochemical reaction in polluted atmosphere. |
| D. | burning of domestic fuel. |
| Answer» C. photochemical reaction in polluted atmosphere. | |
| 144. |
Hydrogen ion concentration in distilled water is |
| A. | 10⁻⁷ |
| B. | 7 x 10⁻⁷ |
| C. | 10⁷ |
| D. | 7 x 10⁷ |
| Answer» B. 7 x 10⁻⁷ | |
| 145. |
Dissolved oxygen content in river water is around __________ ppm. |
| A. | 5 |
| B. | 100 |
| C. | 250 |
| D. | 500 |
| Answer» B. 100 | |
| 146. |
There are thirteen metals which are treated as pollutants. Which of the following metals is not a pollutant ? |
| A. | Mercury |
| B. | Arsenic |
| C. | Aluminium |
| D. | Lead |
| Answer» D. Lead | |
| 147. |
High concentration of carcinogenic hydrocarbon pollutants in atmospheric air causes |
| A. | cancer |
| B. | silicosis |
| C. | respiratory disease (e.g., asthma) |
| D. | reduced crop yield |
| Answer» B. silicosis | |
| 148. |
Out of the following, TLV of __________ is maximum (about 500 ppm). |
| A. | carbon dioxide |
| B. | toluene |
| C. | carbon disulphide |
| D. | acetaldehyde |
| Answer» B. toluene | |
| 149. |
What is the major constituents of waste/polluted water discharged from textile, pulp & paper, tanning, distillary, dairy and meat packing industries ? |
| A. | Radioactive substances |
| B. | Natural organic products |
| C. | Inorganic pollutants |
| D. | None of these |
| Answer» C. Inorganic pollutants | |
| 150. |
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) |
| Answer» E. | |