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  1. The velocity of flow does not depend on

  2. A.

     Grade of sewer

    B.

     Length of sewer

    C.

     Hydraulic mean depth of sewer

    D.

     Roughness of sewer


  3. The slope of sewer shall be

  4. 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


  5. The overflow rate for plain sedimentation tanks is about

  6. A.

     500 to 750 liters/hour/ m²

    B.

     1000 to 1250 liters/hour/ m²

    C.

     1250 to 1500 liters/hour/m²

    D.

     1500 to 2000 liters/hour/m²


  7. The main disadvantage of cement concrete sewers is

  8. A.

     Less strength

    B.

     Difficulty in construction

    C.

     Difficulty in transportation due to heavy weight

    D.

     Less life


  9. Which of the following compounds is widely used for algae control?

  10. A.

     Sodium sulphate

    B.

     Copper sulphate

    C.

     Sodium chloride

    D.

     Calcium chloride


  11. Select the correct statement.

  12. A.

     5 day BOD is the ultimate BOD

    B.

     5 day BOD is greater than 4 day BOD keeping other conditions same

    C.

     5 day BOD is less than 4 day BOD keeping other conditions same

    D.

     BOD does not depend on time


  13. The devices which are installed for drawing water from the sources are called

  14. A.

     Aquifers

    B.

     Aquiclude

    C.

     Filters

    D.

     Intakes


  15. The treatment of water with bleaching powder is known as

  16. A.

     Pre-chlorination

    B.

     Super chlorination

    C.

     De-chlorination

    D.

     Hypo-chlorination


  17. As compared to higher pH values, the contact period required for efficient chlorination at lower pH values is

  18. A.

     Smaller

    B.

     Larger

    C.

     Same

    D.

     None of the above


  19. 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

  20. A.

     Only (i)

    B.

     Both (i) and (ii)

    C.

     Both (i) and (iii)

    D.

     Only (iii)