Multiple Choice Questions and Answers on Environmental Engineering
01. The polluted water is one which
(A) Contains pathogenic bacteria
(B) Consists of undesirable substances rendering it unfit for drinking and domestic use
(C) Is safe and suitable for drinking and domestic use
(D) Is contaminated
Answer: Option B
02. Orthotolidine test is used for determination of
(A) Dissolved oxygen
(B) Residual chlorine
(C) Biochemical oxygen demand
(D) Dose of coagulant
Answer: Option B
03.The chemical most commonly used to increase speed of sedimentation of sewage is
(A) Sulphuric acid
(B) Copper sulphate
(C) Lime
(D) Sodium permanganate
Answer: Option C
04. The disinfection efficiency of chlorine increases by (i) Decreasing the time of contact (ii) Decreasing the temperature of water (iii) Increasing the temperature of water The correct answer is
(A) Only (i)
(B) Both (i) and (ii)
(C) Both (i) and (iii)
(D) Only (iii)
Answer: Option D
05. The layout of distribution system in which water flows towards the outer periphery is
(A) Ring system
(B) Dead end system
(C) Radial system
(D) Grid iron system
Answer: Option C
06. The type of valve which allows water to flow in one direction but prevents its flow in the reverse direction is
(A) Reflux valve
(B) Sluice valve
(C) Air relief valve
(D) Pressure relief valve
Answer: Option A
07. The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is
(A) Separate system
(B) Combined system
(C) Partially separate system
(D) Partially combined system
Answer: Option B
08. The main disadvantage of cement concrete sewers is
(A) Less strength
(B) Difficulty in construction
(C) Difficulty in transportation due to heavy weight
(D) Less life
Answer: Option C
09. Settling velocity increases with
(A) Specific gravity of solid particles
(B) Size of particles
(C) Depth of tank
(D) Temperature of liquid
Answer: Option C
10. Facultative bacteria are able to work in
(A) Presence of oxygen only
(B) Absence of oxygen only
(C) Presence as well as in absence of oxygen
(D) Presence of water
Answer: Option C
11. The suitable layout of distribution system for a city with roads of rectangular pattern is
(A) Grid iron system
(B) Dead end system
(C) Ring system
(D) Radial system
Answer: Option A
12. The slope of sewer shall be
(A) Given in the direction of natural slope of ground
(B) Given in the direction opposite to natural slope of ground
(C) Zero
(D) Steeper than 1 in 20
Answer: Option A
13. The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by
(A) TOD > BOD > COD
(B) TOD > COD > BOD
(C) BOD > COD > TOD
(D) COD > BOD > TOD
Answer: Option B
14. The working conditions in imhoff tanks are
(A) Aerobic only
(B) Anaerobic only
(C) Aerobic in lower compartment and anaerobic in upper compartment
(D) Anaerobic in lower compartment and aerobic in upper compartment
Answer: Option D
15. The pipe which is used to carry the discharge from sanitary fittings like bath rooms, kitchens etc. is called
(A) Waste pipe
(B) Soil pipe
(C) Vent pipe
(D) Anti-siphonage pipe
Answer: Option A
16. If the total hardness of water is greater than its total alkalinity, the carbonate hardness will be equal to
(A) Total alkalinity
(B) Total hardness
(C) Total hardness total alkalinity
(D) Non carbonate hardness
Answer: Option A
17. For a given discharge, the efficiency of sedimentation tank can be increased by
(A) Increasing the depth of tank
(B) Decreasing the depth of tank
(C) Increasing the surface area of tank
(D) Decreasing the surface area of tank
Answer: Option C
18. Air binding phenomena in rapid sand filters occur due to
(A) Excessive negative head
(B) Mud ball formation
(C) Higher turbidity in the effluent
(D) Low temperature
Answer: Option A
19. The suitable method for disinfection of swimming pool water is
(A) Ultra violet rays treatment
(B) Lime treatment
(C) By using potassium permanganate
(D) Chlorination
Answer: Option A
20. 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
(A) Steel
(B) Cast iron
(C) Copper
(D) Reinforced cement concrete
Answer: Option B
21. The water carriage system of collection of waste product
(A) Is cheaper in initial cost than dry conservancy system
(B) Requires treatment before disposal
(C) Creates hygienic problem
(D) All of the above
Answer: Option B
22. The effect of increasing diameter of sewer on the self cleansing velocity is
(A) To decrease it
(B) To increase it
(C) Fluctuating
(D) Nil
Answer: Option B
23. The rate of BOD exerted at any time is
(A) Directly proportional to BOD satisfied
(B) Directly proportional to BOD remaining
(C) Inversely proportional to BOD satisfied
(D) Inversely proportional to BOD remaining
Answer: Option B
24. Generally the detention period for grit chambers is kept as
(A) 1 minute
(B) 5 minutes
(C) 24 hours
(D) 12 hours
Answer: Option A
25. Sludge volume index is defined as the ratio of
(A) Percentage of sludge by volume to percentage of suspended solids by weight
(B) Percentage of sludge by volume to percentage of total solids by weight
(C) Percentage of suspended solids by weight to percentage of sludge by volume
(D) Percentage of total solids by weight to percentage of sludge by volume
Answer: Option A
26. The biochemical treatment of sewage effluents is essentially a process of
(A) Oxidation
(B) Dehydration
(C) Reduction
(D) Alkalinization
Answer: Option A
27. Which of the following causes a decrease in per capita consumption?
(A) Use of metering system
(B) Good quality of water
(C) Better standard of living of the people
(D) Hotter climate
Answer: Option A
28. The suitable method of forecasting population for a young and rapidly increasing city is
(A) Arithmetical increase method
(B) Geometrical increase method
(C) Incremental increase method
(D) Graphical method
Answer: Option B
29. Which of the following is not a water borne disease?
(A) Dysentery
(B) Cholera
(C) Typhoid
(D) Malaria
Answer: Option D
30. Standard EDTA (ethylene diamine tetra acetic acid) solution is used to determine the
(A) Hardness in water
(B) Turbidity in water
(C) Dissolved oxygen in water
(D) Residual chlorine in water
Answer: Option A
31. The settling velocity of a particle in a sedimentation tank depends on
(A) Depth of tank
(B) Surface area of tank
(C) Both depth and surface area of tank
(D) None of the above
Answer: Option B
32. The detention period in coagulation tanks is usually kept as
(A) 1 to 2 minutes
(B) 30 to 45 minutes
(C) 2 to 6 hours
(D) 2 to 6 days
Answer: Option C
33. Period of cleaning of slow sand filters is about
(A) 24 – 48 hours
(B) 10 – 12 days
(C) 2 – 3 months
(D) 1 – 2 year
Answer: Option C
34. The process in which the chlorination is done beyond the break point is known as
(A) Pre-chlorination
(B) Post chlorination
(C) Super chlorination
(D) Break point chlorination
Answer: Option C
35. Disinfection efficiency is
(A) Reduced at higher pH value of water
(B) Unaffected by pH value of water
(C) Increased at higher pH value of water
(D) Highest at pH value equal to 7
Answer: Option A
36. The suitable layout of a distribution system for irregularly growing town is
(A) Dead end system
(B) Grid iron system
(C) Radial system
(D) Ring system
Answer: Option A
37. A sewer that receives the discharge of a number of house sewers is called
(A) House sewer
(B) Lateral sewer
(C) Intercepting sewer
(D) Sub-main sewer
Answer: Option B
38. The time of concentration is defined as
(A) The time taken by rainfall water to run from most distant point of water shed to the inlet of sewer
(B) The time required for flow of water in sewer to the point under consideration
(C) Sum of (A) and (B)
(D) Difference of (A) and (B)
Answer: Option C
39. Most suitable section of sewer in separate sewage system is
(A) Rectangular section
(B) Circular section
(C) Standard form of egg shaped sewer
(D) Modified egg shaped section
Answer: Option B
40. The pathogens can be killed by
(A) Nitrification
(B) Chlorination
(C) Oxidation
(D) None of the above
Answer: Option B
41. The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is
(A) 1 ppm
(B) 4 ppm
(C) 10 ppm
(D) 40 ppm
Answer: Option B
42. If the sewage contains grease and fatty oils, these are removed in
(A) Grit chambers
(B) Detritus tanks
(C) Skimming tanks
(D) Sedimentation tanks
Answer: Option C
43. Composting and lagooning are the methods of
(A) Sludge digestion
(B) Sludge disposal
(C) Sedimentation
(D) Filtration
Answer: Option B
44. The gas from sludge digestion tank is mainly composed of
(A) Nitrogen
(B) Carbon dioxide
(C) Hydrogen sulphide
(D) Methane
Answer: Option D
45. Assertion A: The consumption of water increases with increase in the distribution pressure. Reason R: Higher distribution pressure causes more loss and waste of water Select your answer according to the coding system given below
(A) Both A and R is true and R is the correct explanation of A
(B) Both A and R is true but R is not the correct explanation of A
(C) A is true but R is false
(D) A is false but R is true
Answer: Option A
46. The depression of water table in a well due to pumping will be maximum
(A) At a distance R from the well
(B) Close to the well
(C) At a distance R/2 from the well
(D) None of the above Where ‘R’ is the radius of influence
Answer: Option B
47. Ground water is usually free from
(A) Suspended impurities
(B) Dissolved impurities
(C) Both suspended and dissolved impurities
(D) None of the above
Answer: Option A
48. On standard silica scale, the turbidity in drinking water should be limited to
(A) 10 ppm
(B) 20 ppm
(C) 30 ppm
(D) 50 ppm
Answer: Option A
49. The settling velocity of a particle in a sedimentation tank increases if
(A) Particle size is decreased
(B) The surface area of tank is increased
(C) The depth of tank is decreased
(D) None of the above
Answer: Option D
50. As compared to rapid sand filters, slow sand filters give (i) Slower filtration rate (ii) Higher filtration rate (iii) Lesser efficiency in removal of bacteria (iv) Higher efficiency in removal of bacteria The correct answer is
(A) (i) and (ii)
(B) (ii) and (iii)
(C) (i) and (iv)
(D) (ii) and (iv)
Answer: Option C