Lime reduces the carbonate hardness and soda-ash removes the non-carbonate hardness

Only carbonate hardness is removed

Only noncarbonated hardness is removed

Lime reduces the non-carbonate hardness and soda-ash removes the carbonate hardness

Practice Environmental Engineering Multiple Choice Questions Quiz-3

Q.1

The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally

Less and more
Less and less
More and less
More and more

Q.2

Disinfection efficiency is

Reduced at higher pH value of water
Unaffected by pH value of water
Increased at higher pH value of water
Highest at pH value equal to 7

Q.3

If Biochemical oxygen demand (BOD) of a town is 20000 kg/day and BOD per capita per day is 0.05 kg, then population equivalent of town is

1000
4000
1,00,000
4,00,000

Q.4

The specific gravity of sewage is

Much greater than 1
Slightly less than 1
Equal to 1
Slightly greater than 1

Q.5

The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is

Separate system
Combined system
Partially separate system
Partially combined system

Q.6

In lime-soda process

Only carbonate hardness is removed
Only noncarbonated hardness is removed
Lime reduces the carbonate hardness and soda-ash removes the non-carbonate hardness
Lime reduces the non-carbonate hardness and soda-ash removes the carbonate hardness

Q.7

Scour valves are provided

At street corners to control the flow of water
At every depression and dead ends to drain out the waste water that may collect there
At the foot of rising main along the slope to prevent back running of water
At every summit of rising mains

Q.8

The pipe which is used to carry the discharge from sanitary fittings like bath rooms, kitchens etc. is called

Waste pipe
Soil pipe
Vent pipe
Anti-siphonage pipe

Q.9

The time of concentration is defined as

The time taken by rainfall water to run from most distant point of water shed to the inlet of sewer
The time required for flow of water in sewer to the point under consideration
Sum of (A) and (B)
Difference of (A) and (B)

Q.10

The velocity of flow of water in a sedimentation tank is about

5 to 10 cm/sec
15 to 30 cm/sec
15 to 30 cm/minute
15 to 30 cm/hour

Q.11

The effective size of sand particles used in slow sand filters is

0.25 to 0.35 mm
0.35 to 0.60 mm
0.60 to 1.00 mm
1.00 to 1.80 mm

Q.12

Chlorine demand of water is equal to

Applied chlorine
Residual chlorine
Sum of applied and residual chlorine
Difference of applied and residual chlorine

Q.13

Corrosion in concrete sewers is caused by

Septic conditions
Dissolved oxygen
Chlorine
Nitrogen

Q.14

If the average daily consumption of a city is 100,000 m³, the maximum daily consumption on peak hourly demand will be

100000 m³
150000 m³
180000 m³
270000 m³

Q.15

Sewerage system is designed for

Maximum flow only
Minimum flow only
Average flow only
Maximum and minimum flow

Q.16

Hardy cross method of analysis of distribution system
(i) Involves successive trials
(ii) Takes economic aspects into account
(iii) Is time consuming

Only (i)
(i) and (ii)
(i) and (iii)
All are correct

Q.17

A pipe conveying sewage from plumbing system of a single building to common sewer or point of immediate disposal is called

House sewer
Lateral sewer
Main sewer
Sub-main sewer

Q.18

The depression of water table in a well due to pumping will be maximum
(Where ‘R’ is the radius of influence)

At a distance R from the well
Close to the well
At a distance R/2 from the well
None of the above

Q.19

For normal sludge, the value of sludge index for Indian conditions is

0 to 50
50 to 150
150 to 350
350 to 500

Q.20

The most common cause of acidity in water is

Carbon dioxide
Oxygen
Hydrogen
Nitrogen

Q.21

The percentage of filtered water, which is used for backwashing in rapid sand filters, is about

0.2 to 0.4
0.4 to 1.0
2 to 4
5 to 7

Q.22

The percentage of chlorine in fresh bleaching powder is about

10 to 15
20 to 25
30 to 35
40 to 50

Q.23

The length of rectangular sedimentation tank should not be more than
(Where ‘B’ is the width of the tank)

Q.24

Septic tank is a
(i) Settling tank
(ii) Digestion tank
(iii) Aeration tank

Only (i)
(i) and (ii)
(i) and (iii)
Only (iii)

Q.25

Double filtration is used

To increase the filtration slow sand filters capacity of
To increase the filtration rapid sand filters capacity of
For isolated buildings like pools, hotels etc swimming
All of the above

Q.26

As compared to geometrical increase method of forecasting population, arithmetical increase method gives

Lesser value
Higher value
Same value
Accurate value

Q.27

The rate of BOD exerted at any time is

Directly proportional to BOD satisfied
Directly proportional to BOD remaining
Inversely proportional to BOD satisfied
Inversely proportional to BOD remaining

Q.28

Sludge volume index is defined as the ratio of

Percentage of sludge by volume to percentage of suspended solids by weight
Percentage of sludge by volume to percentage of total solids by weight
Percentage of suspended solids by weight to percentage of sludge by volume
Percentage of total solids by weight to percentage of sludge by volume

Q.29

The maximum permissible limit for fluoride in drinking water is

0.1 mg/liter
1.5 mg/liter
5 mg/liter
10 mg/liter

Q.30

For a country like India, where rainfall is mainly confined to one season, the suitable sewerage system will be

Separate system
Combined system
Partially combined system
Partially separate system