← MES Jr. Grade
Past Questions — 2020
The minimum velocity in sewers to be maintained in order to prevent settlement of sewage solid in the system is :-
A)
0.4 m/s
B)
0.6 m/s
C)
0.8 m/s
D)
0.9 m/s
In sewer design, a minimum self-cleansing velocity is maintained so that suspended solids do not settle and cause blockage. The commonly accepted minimum velocity is about 0.6 m/s. Hence option (b) is correct. The other values are either too low to prevent deposition reliably or are above the standard minimum requirement.
The Ozone depleting potential of Dichlorotetrafluoroethane (C2F4Cl2) is :-
A)
0.6
B)
0.8
C)
1.0
D)
10.0
Dichlorotetrafluoroethane (C2F4Cl2), also known as CFC-114, has an ozone depletion potential (ODP) of about 0.6 relative to CFC-11 (which is taken as 1.0). Therefore, option (a) is correct. The other options do not match the standard ODP value for this compound.
Choose the odd one out from the following water works system :-
A)
Pipe lines
B)
Aqueducts
C)
Open Channels
D)
Tunnels
In a water works system, pipe lines, aqueducts, and tunnels are all generally closed/conveyance structures used to transport water. Open channels, on the other hand, carry water exposed to the atmosphere, so they are the odd one out.
If the pressure surface of Aquifer lies above the ground surface, the well will be :-
A)
Artesian well
B)
Non-artesian well
C)
Non-flowing artesian well
D)
Flowing artesian well
If the pressure surface (piezometric surface) of a confined aquifer lies above the ground surface, water rises in the well and flows out naturally without pumping. This is called a flowing artesian well. An artesian well in general may or may not flow, but when the pressure surface is above ground level, it specifically becomes a flowing artesian well. Non-artesian wells are not under confined pressure, and non-flowing artesian wells have the pressure surface below ground level.
If in a flow-mass curve, a demand line drawn tangent to the lowest in a valley of the curve does not intersect the mass curve at an earlier time period, it represents that :-
A)
the reservoir is full at the beginning of the dry period
B)
the reservoir is wasting water by spill
C)
the storage is inadequate
D)
the reservoir will not be full at the start of the dry period
In a flow-mass curve, a demand line tangent to the lowest point in a valley indicates the minimum storage condition needed to meet demand. If this tangent does not intersect the mass curve at an earlier time, it means there was not enough preceding inflow to fill the reservoir up to the required level before the dry period begins. Hence, the reservoir will not be full at the start of the dry period. Option (b) would apply if the demand line lay below the mass curve causing spill, while (a) and (c) do not match the tangent/no-earlier-intersection condition.
In sedimentation tanks if the horizontal velocity is just sufficient to produce scour then :-
A)
the particles will be carried to the outlet before settling
B)
the particles will be resuspended
C)
scouring will happen at the bottom of the tank
D)
the flow pattern will minimize the effect of inlet and outlet disturbances
In a sedimentation tank, if the horizontal velocity is just sufficient to produce scour, the flow becomes strong enough to disturb the settled or settling particles and lift them back into suspension. That is called scouring/resuspension. Option (a) is about particles being carried to the outlet, which depends on insufficient settling time, not scour. Option (c) is too general and refers to scouring at the bottom, but the key effect described is the resuspension of particles. Option (d) refers to hydraulic design to reduce inlet/outlet disturbances, not scour.
The speed of the Generator in hydro-power plant can be maintained constant only if the speed of the turbine is constant, equal to the one given by the relation (where p is the number of pair of poles for the Generator and f is the frequency for power generated in cycles per second) :-
A)
60f/p
B)
70/p
C)
60/p½
D)
70/p½
In a hydro-power plant, the generator must run at synchronous speed to produce alternating current of frequency f. The synchronous speed is given by N = 120f/P, where P is the total number of poles. Since the question uses p as the number of pairs of poles, P = 2p. Therefore, N = 120f/(2p) = 60f/p. Hence, the correct option is (a). The other options do not match the standard synchronous speed formula.
Choose which of the following equation is independent of the system of units (SI,Metric or English system) :-
A)
Manning’s equation
B)
Chezy’s equation
C)
Laminar flow in pipes
D)
Kennedy’s equation
Manning’s equation is independent of the system of units because it is commonly written with the roughness coefficient n taking values adjusted for the chosen unit system, but the equation itself is not tied to a specific unit form in the way some others are. Chezy’s and Kennedy’s equations involve coefficients that depend on units, and laminar flow in pipes is not a unit-independent empirical flow equation in the same sense. Hence, the correct answer is Manning’s equation.
In hydro-electric power plant, a passage of gradually increasing cross-sectional area connecting the runner exit to the tail race is :-
A)
Scroll casing
B)
Governor
C)
Draft-tube
D)
Runs and platforms
In a hydro-electric power plant, the passage of gradually increasing cross-sectional area connecting the runner exit to the tail race is called a draft tube. It helps recover kinetic energy from water leaving the runner and improves turbine efficiency. Scroll casing distributes water to the runner, the governor controls turbine speed, and runs/platforms are not relevant parts of the turbine passage.
The name D.Thoma of Germany in connection with hydraulic turbine is associated with :-
A)
Performance curves
B)
Efficiency
C)
Specific turbine
D)
Cavitation
D. Thoma of Germany is associated with cavitation in hydraulic turbines. He introduced the concept of Thoma's cavitation coefficient, which is used to predict cavitation conditions. The other options are incorrect because performance curves relate to turbine testing, efficiency is a general performance measure, and specific turbine is not linked to Thoma's name.
Fire hydrants are classified as one-way, two-way, three-way and four-way depending upon :-
A)
The number of hose outlets provided
B)
The number of hose inlets provided
C)
The type of valve of the gate
D)
The diameter of the hydrant
Fire hydrants are classified as one-way, two-way, three-way, and four-way based on the number of hose outlets available for connecting fire hoses. A one-way hydrant has one outlet, a two-way hydrant has two, and so on. The other options are incorrect because hydrants are not classified by hose inlets, valve type, or diameter.
According to Kennedy’s theory the quantity of silt transported is given by Q=aBV5/2 where a is the constant, the value of a as determined by Kennedy is :-
A)
0.5 to 0.4
B)
0.9 to 0.8
C)
1.1 to 1.2
D)
Not determined by Kennedy
Kennedy’s silt transport relation is commonly written in the form Q = a B V^(5/2), where a is an empirical constant. Kennedy determined the value of a approximately in the range 0.8 to 0.9. Therefore, the correct option is (b) 0.9 to 0.8. The other options are incorrect because 0.5–0.4 and 1.1–1.2 do not match Kennedy’s recommended constant, and Kennedy did determine this constant experimentally.
For a given inflow rate in a reservoir :-
A)
trap efficiency increases with the reduction in reservoir capacity
B)
trap efficiency decreases with the increase in reservoir capacity
C)
trap efficiency decreases with the reduction in reservoir capacity
D)
there is no correlation between trap efficiency and reservoir capacity
Trap efficiency is the fraction of incoming sediment retained by a reservoir. For a given inflow rate, a larger reservoir generally has more storage and a longer detention time, so it can trap more sediment. Therefore, when reservoir capacity is reduced, the ability to retain sediment falls and trap efficiency decreases. Hence, option (c) is correct. Options (a) and (b) state the opposite relationship, and (d) is incorrect because trap efficiency does correlate with reservoir capacity.
The most common cause of acidity in water is :-
A)
CO
B)
CO2
C)
NO
D)
H3
The most common cause of acidity in water is carbon dioxide (CO2). When CO2 dissolves in water, it forms carbonic acid (H2CO3), which lowers the pH and makes the water acidic. CO is not the usual cause of acidity, NO is not a direct common cause, and H3 is not a relevant standard chemical species in this context.
The type of plastic generally used for indoor fire sprinkler system since it is suited for use with both hot water and pressurized water is :-
A)
PVC Pipe
B)
UPVC Pipe
C)
CPVC Pipe
D)
PE Pipe
CPVC (Chlorinated Polyvinyl Chloride) is generally used for indoor fire sprinkler systems because it can withstand both hot water and pressurized water. PVC and UPVC are less suitable for higher-temperature hot water applications, while PE is not the standard choice for indoor fire sprinkler piping.
Which of the following is viral type of waterborne disease :-
A)
Salmonellosis
B)
Giardiasis
C)
Poliomyelitis
D)
Shigellosis
Waterborne diseases can be caused by bacteria, protozoa, or viruses. Poliomyelitis is a viral disease caused by poliovirus and can spread through contaminated water. In contrast, Salmonellosis is bacterial, Giardiasis is caused by a protozoan parasite, and Shigellosis is bacterial.
In an area where the danger of waterlogging has become imminent :-
A)
Further canal irrigation should be introduced
B)
No further canal irrigation should be introduced
C)
The area should be irrigated by Tube wells
D)
Both (b) & (c) are recommended
Waterlogging occurs when the water table rises too close to the ground surface, usually due to excessive canal seepage and over-irrigation. In such an area, further canal irrigation should not be introduced because it can worsen the problem. Instead, tube wells are preferred since they help lower the groundwater table by pumping out water. Therefore, both stopping further canal irrigation and using tube wells are correct.
In which type of the following flow of fluid, viscosity plays a significant part :-
A)
Turbulent flow
B)
Laminar flow
C)
Rotational flow
D)
Irrotational flow
Viscosity is the property of a fluid that resists relative motion between adjacent layers. In laminar flow, fluid moves in smooth layers and the viscous effect is significant in determining the motion. In turbulent flow, inertial effects dominate more than viscosity, while rotational/irrotational refer to the nature of flow rotation, not the dominance of viscosity. Hence, the correct answer is laminar flow.
A part of sewer system that receives the discharge from the collecting system and conducts it to the treatment plant or point of final disposal is :-
A)
Sewer outfall
B)
Relief sewer
C)
Lateral sewer
D)
Intercepting sewer
A sewer outfall is the part of the sewer system that carries sewage from the collecting system to the treatment plant or the final disposal point.
Why others are incorrect:
- Relief sewer: used to relieve excess flow in the sewer system.
- Lateral sewer: a small sewer that collects wastewater from individual properties and connects to larger sewers.
- Intercepting sewer: intercepts sewage from several sewers and conveys it to a treatment/disposal point, but the standard definition in this question matches sewer outfall.
Typhoid out break can happen due to infected milk and other foods, particularly oysters, salads and other uncooked food, the epidemic could be waterborne when :-
A)
it is scattered over the city
B)
dysentery accompany or precede typhoid
C)
All classes and ages of people are affected
D)
All of these
Typhoid outbreaks due to contaminated food or water are often recognized as waterborne when the disease is widespread across the city, when dysentery accompanies or precedes typhoid, and when people of all classes and ages are affected. Since all three conditions indicate a common water source affecting many users, the correct answer is "All of these".
Sulfurous smog is caused almost entirely by :-
A)
Motor vehicles
B)
Power plants
C)
Municipal waste
D)
Combination of (a) & (c)
Sulfurous smog (industrial smog or London smog) is mainly produced by the burning of sulfur-containing coal and fuel oil, which releases sulfur dioxide and smoke. This type of pollution is associated almost entirely with power plants and industrial combustion sources. Motor vehicles are more strongly linked with photochemical smog, and municipal waste is not the primary cause of sulfurous smog.
The available hydraulic power possess by a particular stream / river can be assessed in kilowatt-hours (kwh) using the relation, where is the efficiency of hydro power station and others are in usual notations :-
A)
E= 9.81Q(H-h)
B)
E= Q(H-h)
C)
E= 9.81Q(H-h) X T
D)
E= Q(H-h) X T
The hydraulic power available from a stream is proportional to discharge Q, net head (H−h), efficiency η, and time T. Since power in kW is 9.81Q(H−h)η, the energy available in kWh is this power multiplied by time T. Therefore the correct relation is E = 9.81Q(H−h)η × T. Options (a) and (b) give only power-like expressions without time, and (d) misses the 9.81 factor.
The probable maximum flood is :-
A)
an extremely large but physically possible flood in the region
B)
the standard project flood of an extremely large river
C)
a flood adopted in the design of all kinds of spillways
D)
a flood adopted in all hydraulic structures
The probable maximum flood (PMF) is defined as the largest flood that is considered reasonably possible at a site, based on the most severe combination of meteorological and hydrological conditions. It is not a standard project flood, and it is not universally adopted for all spillways or all hydraulic structures. Hence, option (a) is correct.
According to Indian standard recommendation, the uplift pressure in a Gravity dam is assumed to act over :-
A)
100 % of the area
B)
75% of the area
C)
At toe plus 1/3rd the difference of hydrostatic pressure at heel and toe
D)
At heel plus 1/3rd the difference of hydrostatic pressure at heel and toe
In gravity dam analysis as per Indian standard recommendations, uplift pressure is generally assumed to act over 75% of the base area. This reduced-area assumption accounts for the likely effectiveness of drainage and relief measures in lowering uplift. Hence, option (b) is correct. Options (c) and (d) describe the *distribution* of uplift pressure along the base (triangular/trapezoidal pattern), but the question asks about the *area over which uplift is assumed to act*.
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