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WorksheetsEVS - I
Total questions: 50
Worksheet time: 25mins
1. 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
2. The hourly variation factor is usually taken as
a) 1.5
b) 1.8
c) 2.0
d) 2.7
3. If the average daily consumption of a city is 100,000 m3, the maximum daily consumption on peak hourly demand will be
a) 100000m3
b) 150000m3
c) 180000m3
d) 270000m3
4. The distribution mains are designed for
a) maximum daily demand
b) maximum hourly demand
c) average daily demand
d) maximum hourly demand on maximum day
5. As compared to geometric increase method of forecasting population, arithmetical increase method gives
a) lesser value
b) higher value
c) same value
d) accurate value
6. The population of a town in three consecutive years are 5000, 7000 and 8400 respectively. The population of the town in the fourth consecutive year according to geometric increase method is
a) 9500
b) 9800
c) 10100
d) 10920
7. 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
8. The depression of water table in a well due to pumping will be maximum (where R is the radius of influence)
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
9. The devices which are installed for drawing water from the sources are called
a) aquifers
b) aquiclude
c) filters
d) intakes
10. Select the correct relationship between porosity (N) , specify yield (γ) and specific retention (R)
a) N = γ + R
b) γ = N + R
c) R = N + γ
d) R > (N + γ )
11. The type of valve, which is provided on the suction pipe in a tube-well, is
a) air relief valve
b) reflux valve
c) pressure relief valve
d) sluice valve
12. The maximum discharge of a tube-well is about
a) 5 litres/sec
b) 50 litres/sec
c) 590 litres/sec
d) 1000 litres/sec
13. ) As compared to shallow-wells, deep Wells have
a) more depth
b) less depth
c) more discharge
d) less discharge
14. Ground water is usually free from
a) Suspended impurities
b) dissolved impurities
c) both suspended and dissolved impurities
d) none of the above
15. The polluted water is one which
a) contains pathogenic bacteria
b) consists of undesirable substance
c) rendering it unfit for drinking and domestic use
d) is contaminated
16. Which one of the following is not a water borne disease?
a) dysentery
b) cholera
c) typhoid
d) malaria
17. The most common cause of acidity in water is
a) carbon dioxide
b) oxygen
c) hydrogen
d) nitrogen
18. The phenolic permissible limit for fluoride in drinking water
a) 0.1 ppm
b) 0.01 ppm
c) 0.001 ppm
d) 0.0001 ppm
19. The maximum permissible limit for flouride in drinking water is
a) 0.1 mg/litre
b) 1.5 mg/litre
c) 5 mg/litre
d) 10 mg/litre
20. 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
21. Alkaline in water is expressed as milligrams per litre in terms of equivalent
a) calcium carbonate
b) magnesium carbonate
c) sodium carbonate
d) calcium carbonate
22. The product of H+ ions and OH- ions in a stronger alkali is
a) 0
b) 1
c) 10-1
d) 10-14
23. Which of the following values of pH represents a stronger acid ?
a) 2
b) 5
c) 7
d) 10
24. Turbidity is measured on
a) standard silica scale
b) standard cobalt scale
c) standard platinum scale
d) platinum cobalt scale
25. 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
26. Residual chlorine in water is determined by
a) starch iodide method
b) orthotolidine method
c) both (a) and (b)
d) none of the above
27. The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about
a) 0.01 to 0.05 ppm
b) 0.05 to 0.5 ppm
c) 0.5 to 1.0 ppm
d) 1.0 to 5.0 ppm
28. 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
c) total hardness – total alkalinity
29. Orthotolidine test is used for determination of
a) dissolved oxygen
b) residual chloride
c) biochemical oxygen demand
d) dose of coagulant
30. The dissolved oxygen level in natural unpolluted waters at normal temperature is found to be of the order of
a) 1 mg/litre
b) 10 mg/litre
c) 100 mg/litre
d) 1000 mg/litre
31. The velocity of flow of water in a sedimentation tank should not be more than
a) 5 to 10 cm/sec
b) 15 to 30 cm/sec
c) 15 to 30 cm/minute
d) 15 to 30 cm/hour
32. The length of rectangular sedimentation tank should not be more than
(where B is the width of the tank)
a) B
b) 2B
c) 4B
d) 8B
33 . The overflow rate for plain sedimentation tanks is about
a) 500 to 750 litres/hours/m2
b) 1000 to 1250 litres/hours/m2
c) 1250 to 1500 litres/hours/m2
d) 1500 to 2000 litres/hours/m2
34. Percentage of bacterial load that can be removed from the water by the process of plain sedimentation is about
a) 10 to 25
b) 50
c) 75
d) 100
35. The setting 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
36. The setting velocity of a particle in a sedimentation tank increases if
a) particle size is decreases
b) the surface area of tank is decreases
c) the depth of tank is decreases
d) none of the above
37. ) 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
38. The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally
a) less than more
b) less and less
c) more and less
d) more and more
39. Alum as a coagulant is found to be most effective when pH range of water is
a) 2 to 4
b) 4 to 6
c) 6 to 8
d) 8 to 10
40. 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
41. The alum, when added as a coagulant in water
a) does not require alkalinity in water for flocculation
b) does not affect pH value of water
c) increases pH value of water
d) decreases pH value of water
42. The chemical most commonly used to increase speed of sedimentation of sewage is
a) sulphuric acid
b) copper sulphate
c) lime
d) sodium permanganate
43. In water treatment, rapid gravity filters are adopted to remove
a) dissolved organic substances
b) dissolved solids and dissolved gases
c) floating solids and dissolved inorganic solids
d) bacteria and colloidal solid
44. The rate of flirtation in slow sand filters in million litres per day per hectare is about
a) 50 to 60
b) 100 to 150
c) 500 to 600
d) 1400 to 1500
45. The effective size of sand particles used in slow sand filters is
a) 0.25 to 0.35 mm
b) 0.35 to 0.60 mm
c) 0.60 to 1.00 mm
d) 1.00 to 1.80 mm
46. 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
47. The percentage of filtered water, which is used for backwashing in rapid sand filters, is about
a) 0.2 to .04
b) 0.4 to 1.0
c) 2 to 4
d) 5 to 7
48. Period of cleaning of slow sand filters is about
a) 24 -48 hours
b) 10 – 12days
c) 2 – 3 Month
d) 1 – 2 years
49. The rate of filteration of pressure filters is
a) less than that slow sand filters
b) in between the filtration rate of sand filters and rapid sand filters
c) grater than that of rapid sand filters
d) equal to that of slow sand filters
50. Double filtration is used
a) to increase the filtration capacity of slow sand filters
b) to increase the filtration capacity of rapid sand filters
c) for isolated buildings like swimming pools, hotels etc.
d) all of the above
