Hard water for public water supply is discarded because
-
it consumes more soap -
it contains lot of turbidity -
it contains pathogenic bacterias -
it possesses bad taste and odour -
none of these.
Gravity conduits for carrying water from the source are
-
canals -
flumes -
acqueducts -
all the above.
Rapid gravity filter can only remove turbidity of water upto
-
15 to 25 gm/litre -
25 to 30 gm/litre -
30 to 35 cm/litre -
35 to 40 gm/litre -
50 gm/litre.
E. Coli bacterias die in water having pH greater than
-
5.5 -
6.5 -
7.5 -
8.5 -
9.5
The main disadvantage of hard water, is
-
greater soap consumption -
scaling of boilers -
corrosion and incrustation of pipes -
making food tasteless -
all the above.
Surface water is obtained from
-
well -
springs -
artesian well -
rain.
Pick up the correct statement from the following regarding radial flow centrifugal pumps :
-
These are provided with volute type or turbine type casings -
In involute type of radial flow centrifugal pump, the impeller discharges into a gradually expanding spiral casing -
In turbine type of radial flow centrifugal pumps, the impeller is surrounded by stationary guide vanes to reduce the velocity of water -
The efficiency of turbine type of radial flow centrifugal pump, is always higher than that of volute type -
All the above.
Continuous flow of water can be expected from
-
gravity springs -
surface springs -
artesian springs -
none of these.
Pick up the correct statement from the following :
-
The amount of rainfall in 24 hours, is known as daily rainfall -
The amount of rainfall in one year, is known as annual rainfall -
The rain cycle period in India is taken as 35 years -
The ratio of the actual rainfall in the year to the normal rainfall at a place, is called index of the wetness -
All the above.
Check valves are installed
-
on the delivery side of the pumping set -
at the interconnections between polluted water system and a potable water system -
both (a) and (b) -
neither (a) nor (b).
An area is declared drought affected if its mean rainfall is less than
-
50% -
60% -
75% -
80% -
85%.
Hardness of water is caused due to
-
calcium sulphate -
magnesium sulphate -
calcium nitrates -
calcium bicarbonates -
all the above.
Quality of water is said to be good if it is
-
free from suspended matter -
colourless -
free from pathogenic organism -
tasteless -
all the above.
The maximum hourly consumption, is generally taken as
-
110% -
120% -
130% -
140% -
150%.
The best process of disinfection of public water supply, is by
-
boiling -
chlorination -
adding lime -
adding zone.
The best quality of filter material is obtained from quartzite if it does not loose weight when placed in hydro-chloric acid forhours, more than
-
5% -
8% -
10% -
12% -
15%.
Flow through period, in sedimentation tanks, is
-
equal to detention period -
more than detention period -
less than detention period -
detention period divided by displacement efficiency -
none of these.
Pick up the incorrect statement from the following :
-
An impervious layer a few metres below the water table in the sub-soil, is generally called Mota layer (6) Mota layer is very useful to give structural support to open deep wells -
A bore hole is generally provided in the mota layer for deep wells -
Shallow wells are always of less depth as compared to deep wells -
None of these.
A city supply includes
-
domestic water demand -
industrial and commercial water demands -
demand for public uses and fire -
water losses -
all the above.
Pick up the correct statement from the following :
-
A hydrograph is a plot of discharge versus time -
A mass curve is a plot of accumulated flow versus time -
The mass curve continuously rises -
The slope of the mass curve at any time is a measure of the inflow rate at that time -
All the above.
If discharge of a pump is 0.cumecs, the economic diameter of pipe, is
-
0.488 m -
4.88 cm -
0.488 cm -
4.88 m -
none of these.
Normal values of overflow rate for plain sedimentation tank, is
-
250 to 500 litres/hr/m2 -
500 to 750 litres/hr/m2 -
750 to 1000 litres/hr/m2 -
1000 to 1250 litres/hr/m2.
The main draw-back of centrifugal pump, is
-
necessity of priming -
discharge from pump varies with the load of water -
for high heads, efficiency is low up to 50% -
the suction lift is limited to 6 m -
all the above.
If intensity of rainfall in cm per hour is I, percentage coefficient of run-off is P, area of catchment in square kilometres is A, the total run-off Q, is given by
-
Q = 1.758 x 102 x API 
-
Q = 2.758 x 102 x API
-
Q = 2.758 x 103 x API
-
-
If intensity of rainfall in cm per hour is I, percentage coefficient of run-off is P, area of catchment in square kilometres is A, the total run-off Q, is given by
-
Q = 1.758 x 102 x API
-
Q = 2.758 x 102 x API
-
Q = 2.758 x 103 x API
-
-
Mud balls may be removed by
-
breaking and washing -
washing the filter with a solution of caustic soda -
removing, cleaning and replacing the damaged sand -
all the above.
For estimating the run off of catchments, the mean value of the constant 'K' in the Khosla's formula Qy = Py - K (1.8 Ty +is
-
1.21 -
1.23 -
1.25 -
1.27 -
1.31
The maximum pressure to which cast iron pipes may be subjected to, is
-
7 kg/cm2 -
3 kg/cm2 -
5 kg/cm2 -
10 kg/cm2.
For maximum alkalinity of water, pH value should be
-
zero -
less than 7 -
more than 7 -
14 -
21
Service connections to consumers houses, are generally provided with
-
copper pipes -
hume pipes -
galvanised iron pipes -
P.V.C. pipes -
none of these.