← MES Jr. Grade
Past Questions — 2016
Permanent hardness of water can be removed by
A)
adding alum
B)
adding chlorine
C)
zeolite process
D)
all of these
Permanent hardness is caused mainly by calcium and magnesium chlorides and sulphates. It cannot be removed by boiling. The zeolite (permutit) process removes these ions by ion exchange, so it is used to remove permanent hardness. Alum is a coagulant used in water treatment, not for hardness removal, and chlorine is used for disinfection. Therefore, the correct answer is zeolite process.
In a hydro-electric power plant, the turbine used is Pelton wheel. A conical needle is deliberately pushed forward into the nozzle to reduce the amount of water striking the runner. On the other hand, when this needle is pushed back, the amount of water striking the runner increases. This needle is known as
A)
vanes
B)
runner
C)
spear
D)
penstock
In a Pelton wheel turbine, the conical needle inside the nozzle is called the **spear**. It regulates the water flow: when pushed forward, it reduces the jet area and therefore the discharge; when pushed back, it increases the discharge.
Why others are wrong:
- **vanes**: the bucket surfaces on the runner, not the nozzle needle.
- **runner**: the rotating wheel with buckets.
- **penstock**: the pipe carrying water to the turbine.
So, the correct answer is **spear**.
Hardness of water can be removed by boiling if it is due to the presence of
A)
calcium bicarbonates
B)
calcium sulphates
C)
calcium chloride
D)
calcium nitrates
Boiling removes temporary hardness of water, which is caused by bicarbonates of calcium and magnesium. On boiling, calcium bicarbonate decomposes to insoluble calcium carbonate, carbon dioxide, and water, so the hardness is removed. Sulphates, chlorides, and nitrates cause permanent hardness, which is not removed by boiling.
Perched acquifers generally occur
A)
above water table
B)
below water table
C)
in acquicludes
D)
in artesian acquifers
A perched aquifer is a small, isolated body of groundwater that rests on a local impermeable layer above the main regional water table. Hence, it generally occurs above the water table. It is not below the water table, not in aquicludes themselves, and not an artesian aquifer.
The critical gradient for the stability of a structure against seepage pressure according to Khosla’s creep theory is
A)
0
B)
0.50
C)
0.75
D)
1.00
According to Khosla’s creep theory, the critical hydraulic gradient for the stability of a structure against piping/seepage pressure is taken as about 0.5. This means the seepage force should not create a gradient equal to or greater than 0.5, otherwise soil particles may start moving and the structure becomes unsafe. Hence, the correct option is (b) 0.50. The other values are not the standard critical gradient used in this theory.
A well is considered to be good if it is sunk into
A)
Clay
B)
Sand
C)
Coarse gravel
D)
Silt
A good well should be sunk into coarse gravel because gravel has high permeability and can store and yield plenty of groundwater. This allows the well to have a better discharge. Clay and silt are low-permeability soils, so they do not supply water well. Sand can yield water, but coarse gravel is generally better due to larger pore spaces and higher permeability.
Energy equation is usually applicable to
A)
steady flow
B)
non-uniform flow
C)
laminar flow
D)
turbulent flow
The energy equation in fluid mechanics (Bernoulli’s/extended energy equation) is usually applied to steady flow, because it is derived for flow conditions that do not change with time at a given point. In steady flow, properties like velocity, pressure, and density remain constant at a fixed location, making energy balance straightforward.
Why others are incorrect:
- (b) Non-uniform flow: non-uniformity means flow properties change from one point to another, but the standard energy equation is not specifically defined by this condition.
- (c) Laminar flow: laminar flow is a type of flow regime, but the energy equation is not limited to laminar flow.
- (d) Turbulent flow: likewise, the energy equation is not restricted to turbulent flow; it is generally used for steady flow in both laminar and turbulent conditions with appropriate corrections if needed.
Phytometer method is generally used for the measurement of
A)
interception
B)
transpiration
C)
evaporation
D)
precipitation
A phytometer is a device/experimental setup used to estimate the water loss from plants, i.e., transpiration. It works by measuring the amount of water absorbed by a plant under controlled conditions, which approximately equals transpiration. Interception is measured by rainfall and canopy studies, evaporation by pans or lysimeters, and precipitation by rain gauges.
A confined bed of impervious material between acquifers is known as
A)
gravity springs
B)
surface springs
C)
artesian springs
D)
acquicludes
A confined bed of impervious material lying between aquifers is called an acquiclude (also spelled aquiclude). It is a nearly impermeable layer that restricts groundwater flow. The other options are types of springs: gravity springs, surface springs, and artesian springs, so they do not describe the impervious confining layer itself.
The ratio of the rate of change of discharge of an outlet to the rate of change in level of water surface in a distributary at its normal depth is
A)
efficiency
B)
flexibility
C)
sensitivity
D)
modular link
In irrigation engineering, the **sensitivity** of an outlet is defined as the ratio of the rate of change of discharge of the outlet to the rate of change in the water surface level in the distributary at its normal depth. Therefore, the correct term is **sensitivity**.
- **Efficiency** refers to how well water is conveyed or utilized, not this ratio.
- **Flexibility** relates to the ability of a canal/outlet system to supply water over a range of discharges.
- **Modular link** is a type of outlet with constant discharge characteristics, not the ratio itself.
The shear in turbulent flow is mainly due to
A)
heat transfer
B)
mass transfer
C)
momentum transfer
D)
all of these
In turbulent flow, fluid particles move irregularly and mix across layers. This mixing causes exchange of momentum between adjacent layers, producing the additional shear stress called turbulent shear. Heat transfer and mass transfer may occur in turbulent flow, but the primary cause of shear is momentum transfer. Hence, the correct answer is momentum transfer.
The coagulant widely used for sewage treatment is
A)
alum
B)
ferric sulphate
C)
ferric chloride
D)
bleaching powder
In sewage treatment, the most widely used coagulant is alum (aluminium sulphate), because it effectively destabilizes colloidal impurities and helps form flocs that can be removed during sedimentation. Ferric sulphate and ferric chloride are also used as coagulants, but alum is the standard and most common answer in basic environmental engineering MCQs. Bleaching powder is a disinfectant, not a coagulant.
For cereal crops the most commonly adopted method of irrigation is
A)
sprinkler irrigation method
B)
furrow method
C)
free flowing method
D)
check method
For cereal crops, irrigation is commonly done by the furrow method because cereals are generally sown in rows and this method supplies water efficiently to the root zone with less water loss. Sprinkler irrigation is used more for uneven land or light soils, free-flowing method is uncontrolled and inefficient, and check method is mainly used for closely spaced crops like paddy, not for most cereals.
The vertical distance between the total energy line and the hydraulic gradient line is
A)
the pressure head
B)
the piezometric head
C)
the velocity head
D)
none of these
In fluid mechanics, the Total Energy Line (TEL) represents total head = pressure head + velocity head + elevation head. The Hydraulic Gradient Line (HGL) represents piezometric head = pressure head + elevation head. Therefore, the vertical distance between TEL and HGL is the difference: total head − piezometric head = velocity head. Hence, the correct answer is (c).
Type of canal constructed for draining off water from water logged areas are known as
A)
drains
B)
inundation canals
C)
perennial canals
D)
valley canals
Canals constructed specifically to remove excess water from waterlogged areas are called drains. Their function is drainage, not irrigation. Inundation canals carry flood water for irrigation, perennial canals receive continuous supply of water, and valley canals are aligned along valleys and are not meant for draining waterlogged land.
The type of flow in which the velocity at any given time does not change with respect to space is called
A)
steady flow
B)
uniform flow
C)
rotational flow
D)
compressible flow
In fluid mechanics, if the velocity at a given instant does not vary from point to point in space, the flow is called uniform flow. Steady flow means velocity at a point does not change with time, not space. Rotational flow involves rotation of fluid particles, and compressible flow means density changes with pressure.
Precipitation caused due to upward movement of warmer air as compared to surrounding air is called
A)
cyclonic precipitation
B)
orographic precipitation
C)
convective precipitation
D)
conductive precipitation
When the ground heats the air near it, the warmer air becomes lighter and rises upward. As it rises, it cools, moisture condenses, and precipitation occurs. This type is called convective precipitation. Cyclonic precipitation is associated with low-pressure systems and fronts, orographic precipitation occurs when air is forced over mountains, and 'conductive precipitation' is not a standard hydrology term.
The piezometric head is the sum of
A)
velocity head and pressure head
B)
pressure head and elevation head
C)
velocity head and elevation head
D)
none of these
Piezometric head is defined as the sum of pressure head and elevation head, i.e., p/γ + z. It does not include velocity head. Therefore, option (b) is correct. Option (a) is incorrect because velocity head is excluded, and option (c) is incorrect because it does not include pressure head.
In case of laminar flow, the loss of pressure head is proportional to
A)
velocity
B)
velocity2
C)
velocity3
D)
velocity4
For laminar flow in a pipe, the head loss due to friction is given by Hagen–Poiseuille relation, which shows that pressure loss is directly proportional to the mean velocity. Hence, loss of pressure head ∝ velocity. The higher powers of velocity are associated with turbulent flow, not laminar flow.
Useful soil moisture for plant growth is
A)
capillary water
B)
gravity water
C)
hygroscopic water
D)
chemical water
Useful soil moisture for plant growth is capillary water because it is held in the soil pores against gravity and is available to plant roots. Gravity water drains away quickly and is generally not available to plants. Hygroscopic water is tightly adsorbed on soil particles and cannot be used by plants. Chemical water is part of the mineral structure and is also unavailable for plant growth.
In India, the recording type rain gauge generally used is
A)
weighing type
B)
float recording type
C)
tipping type
D)
orographic type
In India, the most commonly used recording rain gauge is the tipping bucket (tipping type) rain gauge because it is simple, reliable, and suitable for measuring rainfall automatically.
Why others are incorrect:
- (a) Weighing type: records rainfall by weighing the collected water, but it is less commonly used in routine Indian observations.
- (b) Float recording type: works with a float mechanism, but it is not the generally used type in India.
- (d) Orographic type: this is not a type of rain gauge; it refers to rainfall caused by mountains, not an instrument.
The maximum velocity in a circular pipe when flow is laminar occurs at
A)
the top of the pipe
B)
the bottom of the pipe
C)
the centre of the pipe
D)
none of these
In laminar flow through a circular pipe, the velocity distribution is parabolic due to the no-slip condition at the wall. The fluid velocity is zero at the pipe wall and increases gradually toward the middle, where it becomes maximum. Hence, the maximum velocity occurs at the centre of the pipe. The top or bottom are not relevant in a circular pipe.
Dissolved carbon di oxide can be removed from the water supply mains by
A)
aeration
B)
chlorination
C)
coagulation
D)
all of these
Dissolved carbon dioxide in water is removed by aeration because it allows the gas to escape from water into the air. Chlorination is used for disinfection, not for removing dissolved gases, and coagulation is used to remove suspended impurities. Therefore, the correct answer is aeration.
The centrifugal pump acts as a reverse of
A)
an inward flow impulse turbine
B)
an inward radial flow reaction turbine
C)
an inward axial flow reaction turbine
D)
a mixed flow type turbine
A centrifugal pump works on the same principle as a turbine but in reverse. In a centrifugal pump, mechanical energy is converted into hydraulic energy, whereas in a turbine hydraulic energy is converted into mechanical energy. Specifically, the centrifugal pump is the reverse of an inward radial flow reaction turbine (like a Francis turbine), because flow in the pump is outward radial, opposite to the inward radial flow in the turbine. Hence option (b) is correct. Option (a) is wrong because impulse turbines do not involve pressure energy conversion in the same way. Options (c) and (d) do not match the radial flow nature of a centrifugal pump.
A modern Francis turbine is
A)
an inward flow impulse turbine
B)
low head axial flow turbine
C)
a high speed axial flow turbine
D)
a mixed flow type turbine
A modern Francis turbine is a reaction turbine in which water enters radially inward and leaves axially outward, so it is classified as a mixed flow turbine. It is not an impulse turbine, and it is neither a pure axial-flow turbine nor specifically a high-speed axial-flow turbine. Hence, the correct option is (d).