Enviroment

Updated: Jul 23, 2020

1 use of metering system- decrease in per capita consumption.


2 The hourly variation factor is. usually taken as-1.5.


3 The distribution mains are designed for-maximum hourly demand on maximum day.


4 The depression of water table in a well due to pumping will be maximum-close to the well.


5 The devices which are installed for drawing waterfromthe sources are called-intakes.


6 The type of valve, which is provided on the suction pipe in a tube-well, is-reflux valve.


7 The maximum discharge of a tube-well is about-50 litres/sec.


8 As compared to shallow-wells, deep wells have-more discharge.


9 Ground water is from-suspended impurities.


10 The polluted water is one which-consists of undesirable substances

rendering it unfit for drinking and domestic use.


11 water borne disease-dysentery,cholera,typhoid.


12 The most common cause of acidity in water is-carbon dioxide.


13 The phenolic compounds in public water supply should not be more than-0.001 ppm.


14 The maximum permissible limit for flouride in drinking water is-1.5 mg/litre.


15 Standard EDTA (ethylene diamine terra acetic acid) solution is used to determine the-hardness in water.


16 Alkalinity in water is expressed as milligrams per litre in terms of equivalent-calcium carbonate.


17 The product of it ions and OH- ions in a stronger alkali is-10-14.


18 Which of the following values of pH represents a stronger acid-2.


19 Turbidity is measured on-standard silica scale.


20 On standard silica scale, the turbidity in drinking water should be limited to-10 ppm.


21 Residual chlorine in water is determined by-starch iodide method,orthotolidine method.


22 The velocity of flow of water in a sedimentation tank is about-15 to 30 cm/minute.


23 The length of rectangular sedimentation tank should not be more than-4B.


24 The overflow rate for plain sedimentation tanks is about-500 to 750 litres/hour/m².


25 The settling velocity of a particle in a sedimentation tank depends on-surface area of tank.


26 For a given discharge, the efficiency of sedimentation tank can be increased by-increasing the surface area of tank.


27 The detention period and overflow rate respectively for plain sedimentation as

compared to sedimentation with coagulation are generally-more and less.


28 The amount of coagulant needed for coagulation of water increases with-increase in turbidity of water,decrease in temperature of water.


29 Alum as a coagulant is found to be most effective when pH range of water is-6 to 8.


30 The detention period in coagulation tanks is usually kept as-2 to 6 hours.


31 The alum, when added as a coagulant in water-increases pH value of water.


32 The effective size of sand particles used in slow sand filters is-0.25 to 0.35 mm.


33 As compared to rapid sand filters, slow sand filters give-slower filtration rate,higher efficiency in removal of bacteria.


34 Air binding phenomena in rapid sand filters occur due to-excessive negative head.


35 The percentage of filtered water, which is used for backwashing in rapid sand filters, is about-2 to 4.


36 Period of cleaning of slow sand filters is about-2 - 3 months.


37 Double filtration is used-to increase the filtration capacity of slow sand filters.


38 Cleaning is done by-scraping and removal in slow sand filters, back washing in rapid sand filters.


39 Disinfection of water results in-killing of disease bacteria.


40 The disinfection efficiency of chlorine increases by-increasing the temperature of water.


41 Chlorine demand of water is equal to-difference of applied and residual

chlorine.


42 The percentage of chlorine in fresh bleaching powder is about-30 to 35.


43 The treatment of water with bleaching. powder is known as-hypochlorination.


44 The suitable method for disinfection of swimming pool water is-ultra violet rays treatment.


45 In chlorination, with the rise in temperature of water, death rate of bacteria-increases.


46 As compared to higher pH values, the contact period required for efficient

chlorination at lower pH values is-smaller.


47 Disinfection efficiency is-reduced at higher pH value of water.


48 In lime-soda process-lime reduces the carbonate hardness and soda-ash removes the non-carbonate hardness.


49 The major disadvantage of lime soda process of water softening is that-huge amount of precipitate is formed which creates a disposal problem.


50 Which of the following compounds is. widely used for algae control -copper sulphate.


51 Activated carbon is used for-removing odours.


52 As compared to cast iron pipes, steel pipes are-stronger.


53 The suitable layout of a distribution system for irregularly growing town is-dead end system.


54 The layout of distribution system in which water flows towards the outer periphery is- radial system.


55 The suitable layout of distribution system fox a city with roads of rectangular pattern is-grid iron system.


56 The commonly used material for water supply pipes, which has the properties of being strong, not easily corroded and long life but is heavy and brittle is-cast iron.


57 Hardy cross method of analysis of distribution system-involves successive trials,is time consuming.


58 The method of analysis of distribution system in which the domestic supply is

neglected and fire demand is considered is-circle method.


59 Which of the following methods of analysis of water distribution system is

most suitable for long and narrow pipe system-equivalent pipe method.


60 Scour valves are provided-at every depression and dead ends to drain out the waste water that may collect there.


61 A sewer that receives the discharge of a number of house sewers is called-lateral sewer.


62 Average rate of water consumption per head per day as per Indian Standard is-135 liters.


63 Sewerage system is usually designed for-25 years.


64 The water carriage system of collection of waste product-requires treatment before disposal.


65 The specific gravity of sewage is-slightly greater than 1


66 The self cleansing velocity for all sewers in India is usually-1.0 m/sec to 1.2 m/sec.


67 The slope of sewer shall be-steeper than 1 in 20.


68 The minimum and maximum diameters of sewers shall preferably be-15 cm and 300 cm.


69 The main disadvantage of cement concrete sewers is-difficulty in transportation due to heavy weight.


70 Most suitable section of sewer in separate sewage system is-circular section.


71 An egg shaped section of sewer-provides self cleansing velocity at

low discharges.


72 The velocity of flow does not depend on-length of sewer.


73 The effect of increasing diameter of sewer on the self cleansing velocity is-to increase it.


74 The most commonly used sewer under culverts is-circular brick sewer.


75 The type of sewer which is suitable for both combined and separate system is-egg shaped sewer.


76 The characteristics of fresh and septic sewage respectively are-alkaline and acidic.


77 The pathogens can be killed by-chlorination.


78 Sewage treatment units are normally designed for-15-20 years.


79 Settling velocity increases With-depth of tank.


80 Standard BOD is measured at-20°C - 5 day.


81 The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is-4 ppm.


82 The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is-100.


83 Dissolved oxygen in streams is-maximum at noon.


84 Facultative bacteria are able to work in-presence as well as in absence of

oxygen

85 The means of access for inspection and cleaning of sewer line is known as- manhole.


86 Sewerage system is designed for-maximum and minimum flow.


87 Sewage treatment units are designed for-average flow only.


88 If the sewage contains grease and fatty oils, these are removed in-skimming tanks.

89 Generally the detention period for grit chambers is kept as-1min.


90 sludge digestion tank-works in anaerobic conditions.


91 The maximum efficiency of BOD removal is achieved in-oxidation ditch.


92 The detention period for oxidation ponds is usually kept as-10 to 15 days.


93 For normal sludge, the value of sludge index for Indian conditions is-150 to 350.


94 When there is no recirculation of sewage,then recirculation factor is-1.


95 A pipe which is installed in the house drainage to preserve the water seal of traps is called-antisiphonage pipe.


96 The gas from sludge digestion tank is mainly composed of-methane.


97 Most of the bacteria in sewage are-saprophytic.


98 The process of lagooning is primarily a means of-disposing of sludge.


99 The biochemical treatment of sewage effluents is essentially a process of-oxidation.


100 Chlorine is used in the treatment of sewage to-help grease separation.


101 In the design of grit chambers-the maximum velocity of flow is 30

cm per second.


102 Ozone layer in the upper atmosphere is getting destroyed owing to its reaction with-chlorofluorocarbons.


103 The intensification of green house effect is attributed to the increased level of-carbon dioxide.


104 The primary pollutant caused by incomplete combustion of organic matter is-carbon monoxide.


105 The spray tower can be used to control-gaseous pollutants,particulate pollutants.


106 The depletion of ozone in the outer atmosphere may result in increased-skin cancer cases.


107 The acid rains are caused by the following pollutants-S02 and Nox.


108 Temporary hardness in water is caused by the presence of-bicarbonate of Ca and Mg.


109 Blue baby disease (methemoglobinemia) in children is caused by the presence of excess-nitrates.


110 If present in water, chlorination of water does not reduce the-dissolved oxygen content.


111 Dechlorination of water is achieved by adding-sodium thiosulphate.


112 The efficiency of a sedimentation tank does not depend upon-depth of the tank.


113 Which of the following treatments reduce salinity of water-Reverse osmosis,Electrodialysis.


114 For the combined sewerage system, eggshaped sewers are preferred because-they offer good flow velocity during the dry-weather-flow condition.


115 Traps are used in household drainage systems to-prevent entry of foul gases in the house.


116 Area method of land filling is most suitable when-adequate depth of cover material is available at the site.

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