Water And Wastewater Engineering Set 5 MCQs

Q1 | The spacing of bars for perforations in coarse screens used for the treatment of sewage, is

20 mm

30 mm

40 mm

50 mm

Q2 | The pH value of fresh sewage is usually

Equal to 7

More than 7

Less than 7

Equal to zero

Q3 | The maximum depth of sedimentation tanks, is kept

3 m

3.5 m

4 m

4.5 m

Q4 | Lead caulked joints are used for laying

Stone ware pipes

Earthenware pipes

C.I. pipes

G.I. pipes

Q5 | If D is the diameter of a circular sewer and D' is the top horizontal diameter of an equivalent eggshaped section, the relationship which holds good, is

D' = 0.64 D

D' = 0.74 D

D' = 0.84 D

D' = 0.94 D

Q6 | The spacing of man holes along a straight portion of a sewer is 300 m, the diameter of the sewermay be

0.9 cm

1.2 m

1.5 m

> 1.5 m

Q7 | The quantity of liquid waste which flows in sewers during the period of rainfall, is known

Sanitary sewage

Industrial waste

Storm sewage

None of these

Q8 | Nitrogen cycle of sewage, is

Liberation of ammonia-formation of nitrites-formation of nitrates-liberation of nitrogen

Liberation of nitrogen-liberation of ammonia-formation of nitrites- formation of nitrates

Liberation of nitrogen-formation of nitrates-formation of nitrites-liberation of ammonia

Formation of nitrates-formation of nitrites-liberation of nitrates-liberation of nitrates

Q9 | Depletion of ozone layer in the outer atmosphere may cause

Lung cancer

Skin cancer

Bronchitis

Heart disorder

Q10 | The minimum diameter of a sewer is kept

10 cm

15 cm

20 cm

25 cm

Q11 | Which one of the following gases is most significant as air pollutant?

Carbondioxide (B) (C) (D)

Oxygen

Nitrogen

Sulphur-dioxide

Q12 | Hazen's formula VS = 418 (GS - Gw)d [(3T + 70)/100] is used for the settlement velocity of theparticles of diameter

Less than 0.01 mm

Less than 0.05 mm

Less than 0.1 mm

Greater than 0.1 mm

Q13 | For sewers, inverted siphon is provided for

One pipe

Two pipes

Three pipes

Four pipes

Q14 | For large sewers, maximum distance between manholes may be

50 m

100 m

200 m

300 m

Q15 | 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

Q16 | The value of Chezy's constant C = 157.6/(1.81 + K/ ?? ) is used in

Chezy's formula

Bazin's formula

Kutter's formula

Manning's formula

Q17 | Pathogens (or pathogenic bacteria’s) in water may cause

Typhoid

Cholera

Dysentery

All the above

Q18 | The rate of accumulation of sludge per person per year, is

10 litres (B) (C) (D)

15 litres

20 litres

25 litres

Q19 | The screens are fixed

Perpendicular to the direction of flow

Parallel to the direction of flow

At an angle 30° to 60° to the direction of flow

None of these

Q20 | In circular sewers if depth of flow is 0.2 times the full depth, the nominal gradient,

Is only provided

Is doubled

Is trebled

Is not enough

Q21 | In detritus tanks

Flow velocity is kept 0.09 m/

Detention period is kept 3 to 4 minutes

Organic and inorganic materials are separated

All the above

Q22 | The flow velocity in detritus tanks is

0.05 m/sec

0.09 m/sec

1.25 m/sec

None of these

Q23 | If the side of a square sewer is 1000 mm, the diameter of a hydraulically equivalent circularsection, is

1045 mm

1065 mm

1075 mm

1095 mm

Q24 | A nuisance is experienced in diluting water if dilution factor is less than

100

60

40

20

Q25 | A manhole is generally provided at each

Bend

Junction

Change of gradient

All the above