← MES Jr. Grade
Past Questions — 2014
Which of the following is an example of free vortex flow?
A)
A whirlpool in a river
B)
Flow of liquid through a hole provided at the bottom of a container
C)
Flow of liquid around a circular bend in a pipe
D)
All of these
A free vortex flow is one in which the fluid rotates without any external torque, and the angular momentum remains constant. A whirlpool in a river is a standard example of free vortex flow. Flow through a hole at the bottom of a container is also often treated as a free vortex-type motion near the outlet, but in standard MCQ context the clearest example given here is the whirlpool. Flow around a circular bend in a pipe is not a free vortex; it is a forced/curved flow due to pressure and boundary effects. Hence, the best answer is (a).
The discharge through a trapezoidal channel is maximum when
A)
half of top width = sloping side
B)
top width = sloping side
C)
top width = 1.5 x sloping side
D)
none of these
For a trapezoidal channel to carry maximum discharge for a given area and slope, it must be the most economical section. In the most economical trapezoidal section, the condition is that half the top width equals the length of one sloping side. This minimizes wetted perimeter for a given area, thereby maximizing hydraulic radius and discharge. Hence option (a) is correct. Options (b) and (c) do not satisfy the standard condition for the most economical trapezoidal channel.
In a reciprocating pump, air vessels are used to
A)
Smoothen the flow
B)
Reduce suction head
C)
Increase delivery head
D)
Reduce acceleration head
In a reciprocating pump, the discharge is pulsating due to the reciprocating motion of the piston. Air vessels store and release water during the cycle, thereby making the flow more uniform or smooth. They also reduce acceleration losses and power fluctuations, but the primary purpose among the given options is to smoothen the flow. Hence, (a) is correct. Options (b) and (c) are unrelated, and (d) is only a secondary effect, not the main use.
Multi-stage centrifugal pumps are used to
A)
Give high discharge
B)
Produce high heads
C)
Pump viscous fluids
D)
All of these
A multi-stage centrifugal pump has two or more impellers in series. The head developed by each stage adds up, so the main purpose is to obtain a much higher discharge pressure/head than a single-stage pump can provide. It is not primarily used to give high discharge, and centrifugal pumps are generally not suitable for highly viscous fluids. Therefore, the correct answer is 'Produce high heads'.
A flood with a return period of 100 years is the flood which occurs
A)
every 100th year
B)
the maximum observed flood in the last 100 years
C)
once in every 100 years on the average
D)
only after 100 years in the immediate future
A 100-year flood means a flood with an annual exceedance probability of 1% in any given year. It does not mean it will occur exactly once in 100 years or only after 100 years. It may occur more than once in a short period or not at all for more than 100 years. Hence, the correct interpretation is 'once in every 100 years on the average.'
In the case of water table well, the piezometric surface
A)
is above the ground level
B)
is below the water level in the well
C)
coincides with water level in the well
D)
is between the water level in the well and ground level
In a water table well, the well taps an unconfined aquifer. The water level in the well stands at the same level as the water table, which is the piezometric surface for an unconfined aquifer. Therefore, the piezometric surface coincides with the water level in the well. The other options are incorrect because the piezometric surface being above ground level applies to artesian conditions, and it is not below or between the water level and ground level in a water table well.
Zero hardness of water is achieved by
A)
lime soda process
B)
excess lime treatment
C)
ion exchange treatment
D)
excess alum and lime treatment
Zero hardness means essentially complete removal of calcium and magnesium ions. This is achieved by ion exchange treatment (zeolite/resin process), where hardness-causing ions are exchanged with sodium ions, producing water with nearly zero hardness. Lime-soda and excess lime treatments reduce hardness but do not usually remove it completely, so they do not give zero hardness.
In selecting site for a rain gauge the nearest object should be at a minimum distance of
A)
twice its height
B)
three times its height
C)
equal to its height
D)
anywhere
A rain gauge should be installed in an open area so that nearby objects do not obstruct rainfall. The nearest object should be at least three times its height away from the gauge. This reduces wind effects and splash/interference. Hence, option (b) is correct. Options (a) and (c) are too close, and (d) is incorrect because site selection matters.
A pumped storage plant is a
A)
High head plant
B)
Peak load point
C)
Runoff river plant
D)
Base Load plant
A pumped storage plant is used to store energy by pumping water to an upper reservoir during off-peak hours and generating power during peak demand. Therefore, it is primarily a peak load plant. It is not a run-of-river plant, which depends on natural river flow, nor a base load plant, which supplies continuous power. While pumped storage plants are often associated with high heads, the defining classification here is peak load operation.
The velocity of flow in a sewer should be between
A)
0.6 m/sec and 3 m/sec
B)
2 m/sec and 10 m/sec
C)
30 cm/sec and 90 cm/sec
D)
30 m/sec and 90 m/sec
In sewer design, the self-cleansing velocity should be high enough to prevent deposition of solids, but not so high that it causes abrasion or damage to the sewer. The commonly accepted range is about 0.6 m/s to 3 m/s. Hence, option (a) is correct. The other options are either too low to prevent silting or unrealistically high for sewer flow.
Which of the following methods of applying water may be used on rolling land?
A)
Border flooding
B)
Check flooding
C)
Furrow flooding
D)
Free Flooding
Rolling or uneven land is best suited to furrow irrigation because water flows in small channels between crop rows, reducing runoff and allowing better control on sloping ground. Border flooding and check flooding generally require fairly level land, while free flooding is uncontrolled and not suitable for rolling land.
An ideal fluid is
A)
One which obeys Newton’s law of Viscosity
B)
Frictionless and Incompressible
C)
Very Viscous
D)
Frictionless and Compressible
An ideal fluid is a hypothetical fluid that has no viscosity, so it offers no internal friction, and it is taken as incompressible. Hence, the correct description is "frictionless and incompressible." Option (a) is wrong because Newton’s law of viscosity applies to real fluids with viscosity. Option (c) is the opposite of ideal behavior. Option (d) is wrong because ideal fluids are not compressible in standard fluid mechanics assumptions.
For the best rectangular open channel section, the depth Y and bed width b are related by
A)
Y=b/3
B)
Y=b
C)
Y=b/2
D)
Y=b/4
For the most economical (best) rectangular open channel section, the hydraulic radius is maximized for a given area. For a rectangular channel, this condition gives bed width b = 2Y, where Y is the depth of flow. Hence, Y = b/2. Therefore, option (c) is correct. The other options do not satisfy the standard best-section condition.
The target reliability of irrigation release under normal conditions is
A)
100%
B)
90%
C)
75%
D)
50%
In irrigation planning, the target reliability of irrigation release under normal conditions is generally taken as 90%. This means the designed water supply should meet the demand in about 9 out of 10 normal years. 100% is not practical because some uncertainty and variability in inflow and demand always remain, while 75% and 50% are too low for a normal-condition design standard.
Surge tank in a hydropower project is used to
A)
Reduce water hammer pressure
B)
Store water
C)
Regulate discharge in the power house
D)
Control sediments entering the turbine
A surge tank is provided in a hydropower system to absorb sudden changes in flow caused by rapid load variations. It helps reduce pressure fluctuations and water hammer in the penstock. It is not mainly for storing water, regulating discharge in the powerhouse, or controlling sediments.
Double mass curve technique is used
A)
to prepare rainfall hyetograph
B)
to derive the hydrograph
C)
to derive the S-curve hydrograph
D)
to check the consistency of rainfall records
The double mass curve technique is a hydrological method used to test the consistency of rainfall data. It compares cumulative rainfall at a station with cumulative rainfall of nearby stations or a reference group. If the slope changes, it indicates inconsistency due to changes in gauge location, exposure, instruments, or observing practices. It is not used to prepare a hyetograph, derive a hydrograph, or derive an S-curve hydrograph.
If the duration of the unit hydrograph approaches zero, the resulting unit hydrograph is known as
A)
The limiting unit hydrograph
B)
The threshold unit hydrograph
C)
The instantaneous unit hydrograph
D)
The saturated unit hydrograph
A unit hydrograph is derived for a rainfall excess of a specified duration. When this duration approaches zero, the hydrograph obtained is called the instantaneous unit hydrograph (IUH). It represents the direct runoff response to an infinitesimally short burst of effective rainfall. The other options are not standard hydrology terms for this concept.
Slow sand filter is more efficient for the removal of
A)
Bacteria
B)
Odour
C)
Turbidity
D)
All of these
Slow sand filters are especially effective in removing bacteria and other microorganisms because a biological layer (schmutzdecke) develops on the sand surface and helps in purification. They also reduce turbidity to some extent, but their most efficient removal is of bacteria. Odour removal is not their primary strength. Hence, the correct answer is Bacteria.
The flow in open channel is laminar if the Reynold number is
A)
2000
B)
less than 2000
C)
less than 5000
D)
none of these
For open channel flow, the Reynolds number criterion is commonly taken as: laminar flow for Re < 500, transitional flow for Re between 500 and 2000, and turbulent flow for Re > 2000. Therefore, the flow is laminar when the Reynolds number is less than 2000. Option (a) is not a condition but a value, and (c) is too high for laminar flow.
The average domestic demand of water for an Indian city is
A)
135 lpcd
B)
270 lpcd
C)
500 lpcd
D)
750 lpcd
For an Indian city, the standard average domestic water demand is about 135 litres per capita per day (lpcd), as commonly used in water supply and environmental engineering norms. The other values are too high for average domestic demand: 270 lpcd and above are not typical Indian urban domestic norms.
A current meter is used to measure the
A)
Velocity of flow of water
B)
Depth of flow of water
C)
Discharge
D)
None of these
A current meter is an instrument used in fluid mechanics to measure the velocity of flowing water at a point. It does not directly measure depth or discharge. Discharge is usually computed separately using velocity measurements and cross-sectional area.
A flood is given a rank m in an observed record of n years. Then according to Weibul’s formula, its return period is given by
A)
n/m
B)
n/(m+1)
C)
n/(m-1)
D)
(n+1)/m
According to Weibull’s plotting position formula, the return period T of a flood ranked m in an observed record of n years is T = n/m. Here, m is the rank of the flood event in descending order of magnitude. The other options do not match Weibull’s standard formula.
A hydrograph is the graph drawn between
A)
discharge in the river and stage in the river
B)
discharge and time
C)
stage and time
D)
none of these
A hydrograph is the plot of stream discharge against time at a given point on a river. It shows how flow varies with time, especially during rainfall-runoff events. Option (a) describes a rating curve, and option (c) is a stage hydrograph, not the general definition of a hydrograph.
A canal aligned approximately parallel to the natural drainage of a country is called
A)
Side slope canal
B)
Contour canal
C)
Watershed canal
D)
Ridge canal
A canal aligned approximately parallel to the natural drainage of a country is called a side slope canal. Such canals generally follow the side slope of the terrain. A contour canal follows a contour line, a watershed canal runs along the watershed or ridge line, and a ridge canal is located on the ridge between two drainage basins.
The difference in elevations of top of bank and full supply level of a canal is called
A)
berm
B)
critical depth
C)
free board
D)
surcharge depth
The difference in elevation between the top of the canal bank and the full supply level is called the free board. It provides safety against overtopping due to waves, fluctuations, and settlement. Berm is a horizontal strip, critical depth is a hydraulic term, and surcharge depth refers to water above the designed full supply level in exceptional conditions.