Q.1
The maximum diameter of sewers adopted in the designs is
Q.2
Which one of the following part of human body withstands minimum radiation?
Q.3
Hydraulic mean radius is
Q.4
Hazen’s formula VS = 418 (GS – Gw)d [(3T + 70)/100] is used for the settlement velocity of the particles of diameter
Q.5
The sewer which resists sulphide corrosion, is
Q.6

The sewerage system consists of

  • house sewer
  • lateral sewer
  • branch sewer
  • main sewer
  • all of these.
Q.7

Sewer pipes need be checked for

  • minimum flow
  • maximum flow
  • both (a) and (b)
  • none of these.
Q.8

The settlement velocity of a solid (diameter 0.5 mm, specific gravity 1.in water having temperature 10°C, is

  • 213.5 cm/sec
  • 313.5 cm/sec
  • 413.5 cm/sec
  • 500 cm/sec.
Q.9

If D.O. concentration falls down to zero in any natural drainage, it indicates the zone of

  • degradation
  • active decomposition
  • recovery
  • cleaner water
  • none of these.
Q.10

Aerobic activity is maximum

  • in freshly produced sewage
  • at sewer pipes
  • in sewer treatment plants
  • none of these.
Q.11

The minimum diameter of a sewer is kept

  • 10 cm
  • 15 cm
  • 20 cm
  • 25 cm
  • 30 cm.
Q.12

If γw is the unit weight of water, r the hydraulic mean depth of the sewer and S the bed slope of the sewer, then the tractive force exerted by flowing water, is

  • γw . r . S
  • γw r1/2 . S
  • γw r S
  • γw r2/3 S
Q.13

The ratio of design discharge to the surface area of a sedimentation tank is called

  • surface loading
  • overflow rate
  • overflow velocity
  • all of these.
Q.14

In sewers designed with self cleansing velocity,

  • the bottom is silted
  • the bottom is scoured
  • both silting and scouring occur at the bottom
  • neither silting nor scouring occurs at the bottom.
Q.15

The minimum diameter of sewer to be adopted is

  • 10 cm
  • 12.5 cm
  • 15 cm
  • 25 cm.
Q.16

In detritus tanks,

  • flow velocity is kept 0.09 m/sec
  • detention period is kept 3 to 4 minutes
  • organic and inorganic materials are separated
  • all the above.
Q.17

Inkg of sewage, the total solids approximate

  • 0.5 to 1.0 kg
  • 1 kg to 2.0 kg
  • 5 kg to 7.5 kg
  • 7.5 kg to 10 kg.
Q.18

Stone ware pipes are

  • highly resistant to sulphide corrosion
  • highly impervious
  • hydraulically efficient because of their smooth interior surface
  • specially suited to pressure pipes
  • none of these.
Q.19

Which one of the following resists hydrogen sulphide corrosion

  • R.C.C.
  • Glazed stone wares
  • Asbestos cement
  • Glazed ware.
Q.20

D is the diameter of a circular sewer and α is the side of a square section sewer. If both are hydraulically equivalent, the relationship which holds good, is

  • πD8/3 = 4 b8/3
  • πD3/8 = 4 b3/8
  • πD2/3 = 4 b2/3
  • πD3/2 = 4 b3/2
  • none of these.
Q.21

To test chemical oxygen demand (C.O.D.) of sewage, organic matter is oxidised by pottassium dichromate in the presence of

  • Hydrochloric acid
  • Sulphuric acid
  • Nitric acid
  • Citric acid.
Q.22

The width of a settling tank with 2 hour detention period for treating sewagecu m per hour, is

  • 5 m
  • 5.5 m
  • 6 m
  • 6.5 m
  • 7 m.
Q.23

Pathogens (or pathogentic bacterias) in water may cause

  • typhoid
  • cholera
  • dysentery
  • infectious hepatitis
  • all the above.
Q.24

In the activated sludge process

  • aeration is continued till stability
  • aeration is done with an admixture of previously aerated sludge
  • sludge is activated by constant stirring
  • water is removed by centrifugal action.
Q.25

Skimming tanks are

  • used to remove the grease and oil
  • those from which sludge is skimmed out
  • tanks provided with self-cleansing screens
  • improved version of grit chambers.
Q.26

The settlement of a particle in sedimentation tank, is affected by

  • velocity of flow
  • viscosity of water
  • size and shape of solid
  • specific gravity of solid
  • all the above.
Q.27

For detecting the nitrites in the sewage, the matching colour may be developed by adding

  • Pottassium permanganate
  • Sulphuric acid and napthamine
  • Phenol-di-sulphuric acid pottassium hydroxide
  • None of these.
Q.28

If n is the rugosity coefficient, r is the hydraulic depth, s is the bed slope of sewer, the velocity of flow in m/sec may be obtained by the formula evolved by

  • Chezy
  • Manning
  • Bazin
  • Kutter.
Q.29

The discharge per unit plan area of a sedimentation tank, is generally called

  • over flow rate
  • surface loading
  • over flow velocity
  • all the above.
Q.30

In areas where rainy season is limited to a few months, the type of sewerage system recommended is

  • combined system
  • partially separate system
  • separate system
  • none of these.
Q.31

Sewer manholes are generally provided at

  • the change of gradient
  • the change of direction
  • the junctions of sewers
  • all of these.
Q.32

Pick up the correct statement from the following :

  • anaerobic bacteria flourish in the absence of oxygen
  • aerobic bacteria flourish in the presence of oxygen
  • facultative bacteria flourish with or without oxygen
  • all the above.
Q.33

If the length of overland flow from the critical point to the mouth of drain is 13.km and difference in level between the critical point and drain mouth ism, the inlet time is

  • 2 hours
  • 4 hours
  • 6 hours
  • 8 hours.
Q.34

Hume steel pipes are

  • steel pipes
  • R.C.C. pipes
  • steel shell coated from inside with cement mortar
  • steel shell coated from outside with cement mortar
  • both (c) and (d).
Q.35

The suitable cross-section of sewers to carry combined flow, is

  • circular
  • egg shaped
  • rectangular
  • horse shoe shaped.
Q.36

Assertion (A) : The determination of pH value of sewerage is important.

Reason (R) : The efficiency of certain treatment methods depends upon the availability of pH value.

  • Both A and R are true and R is the correct explanation of A
  • Both A and R are true but R is not a correct explanation of A
  • A is true but R is false
  • A is false but R is true.
Q.37

Antisyphonage pipe is fitted

  • at the end of septic tanks
  • on manholes
  • with a W.C. trap
  • at the beginning of sewer line.
Q.38

Oxidation process results in the formation of

  • carbon dioxide
  • nitrates
  • sulphates
  • all the above.
Q.39

Before discharging the foul sewage into rivers, it is generally treated by

  • screening
  • sedimentation
  • oxidation
  • sludge digestion and disinfection
  • all the above.
Q.40

With self cleansing velocity in sewers

  • silting occurs at bottom
  • scouring occurs at bottom
  • both silting and scouring occur at bottom
  • neither silting nor scouring occurs at bottom.
Q.41

For drains up tocumecs, the depth d and width B are related by

  • d = 0.2 B
  • d = 0.5 B
  • B = 0.2 d
  • B = 0.5 d.
Q.42

Dry weather flow is :

  • average daily rate of flow
  • average monthly rate of flow
  • average annual rate of flow
  • water supply allowance per capita
  • none of these.
Q.43

If the diameter of a sewer ismm, the gradient required for generating self cleansing velocity, is

  • 1 in 60
  • 1 in 100
  • 1 in 120
  • none of these.
Q.44

Before discharging the foul sewage into rivers, it is generally treated by

  • screening
  • sedimentation
  • oxidation
  • sludge digestion and disinfection
  • all the above.
Q.45

As compared to fresh river water, sea water contains oxygen

  • 10% less
  • 20% less
  • 10% more
  • 20% more.
Q.46

In the activated sludge process

  • aeration is continued till stability
  • aeration is done with an admixture of previously aerated sludge
  • sludge is activated by constant stirring
  • water is removed by centrifugal action.
Q.47

For drains up tocumecs, the depth d and width B are related by

  • d = 0.2 B
  • d = 0.5 B
  • B = 0.2 d
  • B = 0.5 d.
Q.48

With self cleansing velocity in sewers

  • silting occurs at bottom
  • scouring occurs at bottom
  • both silting and scouring occur at bottom
  • neither silting nor scouring occurs at bottom.
Q.49

In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for a discharge Q, is

Q.50

If the diameter of a sewer ismm, the gradient required for generating self cleansing velocity, is

  • 1 in 60
  • 1 in 100
  • 1 in 120
  • none of these.
0 h : 0 m : 1 s