SSC-JE, AE(PSC), RRB JE etc.
Objective Questions
(81 to 90)
Environmental
Engineering
Q. 81) The type of valve which is provided to control the
flow of water in the distribution system at street corners
and where the pipe lines intersect is
A. Check valve
B. Sluice valve
C. Safety valve
D. Scour valve
Answer B A. Check valve, non-return valve, reflux valve:- is a valve that
normally allows fluid to flow through it in only one direction.
B. Sluice valve:- are movable gates set over a moving body of water that
control the quantity of water permitted to flow through the gate. Raising
the gate increases water flow, and lowering the gate reduces it. It is
provided to control the flow of water in the distribution system at street
corners and where the pipe lines intersect.
C. Safety Valve:- Valve that automatically actuates when the pressure of
inlet side of the valve increases to a predetermined pressure, to open the
valve disc and discharge the fluid (steam or gas ) ; and when the pressure
decreases to the prescribed value, to close the valve disc again.
D. Scour valves:- are located at low points or at every depression and
dead ends of the pipeline. Their function is to allow periodic flushing of
the lines to remove sediment and to allow the line to be drained for
maintenance and repair work.
Q. 82) The type of valve which allows water to flow in one
direction but prevents its flow in the reverse direction is
A. Reflux valve
B. Sluice valve
C. Air relief valve
D. Pressure relief valve
Answer A
Q. 83) Scour valves are provided
A. At street corners to control the flow of water
B. At every depression and dead ends to drain out the
waste water that may collect there
C. At the foot of rising main along the slope to prevent
back running of water
D. At every summit of rising mains
Answer B
A. Sluice valves
B. Scour valves
C. Reflux valves
Q. 84) A sewer that receives the discharge of a number of
house sewers is called
A. House sewer
B. Lateral sewer
C. Intercepting sewer
D. Submain sewer
Answer B
1. House sewer:- A pipe conveying sewage from plumbing system of
single building and delivers it to the lateral sewer.
1. Lateral sewer:- The sewer which obtains its discharge directly from
buildings (house sewers).
2. Branch or sub-main sewer:- The sewer which obtains its discharge from
a few laterals and delivers it to the main sewer.
3. Main Sewer:- The sewer which obtains its discharge from a few branch
or sub-main sewers.
4. Trunk Sewer:- The sewer which obtains its discharge from two or more
main sewers.
5. Intercepting sewer:- The sewer which obtains the discharge from a
number of main or outfall sewer and carries the same to the point of
treatment and disposal.
Q. 85) A pipe conveying sewage from plumbing system of
single building to common sewer or point of immediate
disposal is called
A. House sewer
B. Lateral sewer
C. Main sewer
D. Submain sewer
Answer A
Q. 86) For a country like India, where rainfall is mainly
confined to one season, the suitable sewerage system will
be
A. Separate system
B. Combined system
C. Partially combined system
D. Partially separate system
Answer A
The sewage systems are classified as follows:
1. Combined system:- When only one set of sewers is laid, carrying both
the sanitary sewage and storm water.
2. Separate system:- When the domestic and industrial sewage are taken
in one set of sewers, whereas storm and surface water are taken in
another set of sewers.
3. Partially separate/combined system:- In the separate system, if a
portion of storm water is allowed to enter in the sewers carrying sewage,
and the remaining storm water flows in separate set of sewers.
The combined system is used:-
1. In areas having small rainfall which is evenly distributed throughout the
area, because at such places self-cleaning velocity will be available in
every season.
2. Used in crowded areas, where it is very difficult to lay two sewers.
3. In area having less sewage, to obtain the self-cleaning velocity.
The separate system is used:-
1. If rainfall is mainly in one seasons. (because in combined system self-
cleaning velocity will not be available for most of the period of the years)
2. In rocky areas it is more expensive to lay one large sewer.
3. If the sanitary sewage is to be pumped.
Q. 87) Average rate of water consumption per head per
day as per Indian Standard is
A. 100 litres
B. 135 litres
C. 165 litres
D. 200 litres
Answer B
Q. 88) Sewerage system is usually designed for
A. 10 years
B. 25 years
C. 50 years
D. 75 years
Answer B
The design period for sewerage systems may be not less than 20
years and not more than 30 years.
Q. 89) Which of the following sewers is preferred for
combined system of sewage?
A. Circular sewer
B. Egg shaped sewer
C. Rectangular sewer
D. None of the above
Answer B
The Egg shaped sewer provides slightly higher velocity for low
flows over the circular sewer of equal capacity.
This makes it useful during combined sewerage system.
Q. 90) the suitable system of sanitation for area of
distributed rainfall throughout the year with less intensity
is
A. Separate system
B. Combined system
C. Partially separate system
D. Partially combined system
Answer B
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