Public Health Engineering (PHE)



Multiple Choice Questions (MCQs)
1   Aeration of water is done to remove
    (A)   Odour
    (B)   Colour
    (C)   Bacterias
    (D)   Turbidity

2   The maximum permissible nitrites in public water supplies, is
    (A)   Nil
    (B)   0.5 PPM
    (C)   1 PPM
    (D)   1.5 PPM

3   Chemical coagulation of drinking water, is done
    (A)   To settle suspended materials
    (B)   To increase rate of settlement of suspended materials
    (C)   To remove the bacteria
    (D)   None of these

4   Rapid gravity filters
    (A)   Were developed by G.W. Fuller
    (B)   Make use of coarser sand with effective size as 0.5 mm
    (C)   Yield as high as 30 times the yield of slow sand filters
    (D)   All the above

5   The detention period for plain sedimentation water tanks, is usually
    (A)   4 to 8 hours
    (B)   8 to 16 hours
    (C)   16 to 24 hours
    (D)   24 to 36 hours

6   Most satisfactory formula for an estimate of fire demand Q for a city of population P in thousands for Indian conditions, is
    (A)   Q = 1115 (p/5 + 20)
    (B)   Q = 1640 √P (1 – 0.01 √P)
    (C)   Q = 3180 √P
    (D)   None of these

7   After cleaning a slow sand filter, the filtered water is not used for
    (A)   6 hours to 12 hours
    (B)   12 hours to 18 hours
    (C)   18 hours to 24 hours
    (D)   24 hours to 36 hours

8   The best process of disinfection of public water supply, is by
    (A)   Boiling
    (B)   Chlorination
    (C)   Adding lime
    (D)   Adding ozone

9   When the reduced level of the water source is higher than the reduced level of the consumer’s place, water is generally supplied
    (A)   By pumping system
    (B)   By gravitational system
    (C)   Both (a) and (b)
    (D)   All the above

10   For the prediction of future population of a city, the factor to be considered, is
    (A)   Births
    (B)   Deaths
    (C)   Migrants
    (D)   All the above

11   A city supply includes
    (A)   Domestic water demand
    (B)   Industrial and commercial water demands
    (C)   Demand for public uses and fire
    (D)   All the above

12   Turbidity is the ability of water to
    (A)   Scatter light
    (B)   Retain suspended solids
    (C)   Retain colloidal solids in suspension
    (D)   Detain dissolved solids

13   Turbidity for domestic water is undesirable because it’s
    (A)   Is unaesthetic
    (B)   Causes change of taste
    (C)   Give apparent colour
    (D)   Prevents light penetration & hence photosynthesis

14   Higher pH for water is undesirable because
    (A)   It corrodes zinc, copper & lead pipes
    (B)   It includes sour taste
    (C)   It renders chlorination less effective
    (D)   It promotes growth of iron & sulphur bacteria

15   Presence of nitrogen in a waste water sample is due to the decomposition of
    (A)   Carbohydrates
    (B)   Proteins
    (C)   Fats
    (D)   Vitamins

16   More than 1mg/l of fluorides causes
    (A)   Dental caries
    (B)   Mottled enamel of teeth
    (C)   Skeletal fluorosis
    (D)   Prevent dental cavaties & tooth decay in children

17   A desirable feature of hardness is
    (A)   More soap consumed
    (B)   Skin roughened
    (C)   Vegetables toughened
    (D)   Scales formed inside pipes to protect them from corrosion

18   A factor affecting domestic demand of water is
    (A)   Dead end system or rectification of network of pipes
    (B)   Timing of water supply
    (C)   Water supplies is soft or hard
    (D)   Climatic conditions

19   For an old city with constraints for growth the best method of forecasting future population is
    (A)   Arthimatical increase method
    (B)   Geometrical increase method
    (C)   Graphical method
    (D)   Incremental increase method

20   Design period mainly depends on
    (A)   Percentage interest at which the loan is taken
    (B)   Capacity of the municipality to repay
    (C)   Quality of fittings used
    (D)   Rate of growth of population

21   A river intake may be situated on
    (A)   A straight reach
    (B)   The convex side of a curved course
    (C)   Downstream side of outfall sewer
    (D)   Proximity to industries

22   Sedimentation may not be required for water from a
    (A)   Shallow well
    (B)   Deep well
    (C)   River
    (D)   Canal

23   Permissible velocity through coarse screens is not greater than
    (A)   1m/s
    (B)   1m/min
    (C)   0.3 m/ s
    (D)   0.3 m/min

24   Coagulating power of a chemical increases with its
    (A)   Atomic weight
    (B)   Molecular weight
    (C)   Density
    (D)   Valency

25   Optimum dose of coagulant means the least dose that produces
    (A)   Maximum amount of floc
    (B)   Floc whose density is very high
    (C)   Max. Amount of floc within the least time
    (D)   Readily settleable floc

26   Schmutzdecke will be formed in
    (A)   Slow sand filters
    (B)   Rapid sand filters
    (C)   Pressure filters
    (D)   Both SSF & RSF

27   Backwashing is highly effective in case of
    (A)   SSF
    (B)   RSF
    (C)   Pressure filters
    (D)   Both RSF & SSF

28   Coagulant may not be added for treatment before
    (A)   Slow sand filter
    (B)   Rapid sand filter
    (C)   Pressure filter
    (D)   Both in RSF & SSF

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