Technical · Civil Engineering
Hydraulics and Environmental Engineering MCQs for placement tests
20 technical questions of moderate difficulty, as asked in campus placement and company tests. Each has a short explanation.
Q1Civil · Hydraulics and Environmental EngineeringModerate
Manning's formula is used to calculate:
Solution
V = (1/n) R2/3 S1/2.
Answer: (D) Velocity of flow in open channels
Q2Civil · Hydraulics and Environmental EngineeringModerate
The hydraulic radius of a channel is:
Solution
R = A/P.
Answer: (B) Area of flow divided by wetted perimeter
Q3Civil · Hydraulics and Environmental EngineeringModerate
The most economical rectangular channel section has a width equal to:
Solution
b = 2y minimises the wetted perimeter for a given area.
Answer: (B) Twice the depth
Q4Civil · Hydraulics and Environmental EngineeringModerate
Flow in an open channel is subcritical when the Froude number is:
Solution
Fr < 1 is subcritical, Fr > 1 is supercritical.
Answer: (C) Less than 1
Q5Civil · Hydraulics and Environmental EngineeringModerate
A hydraulic jump occurs when flow changes from:
Solution
It dissipates energy, for example below spillways.
Answer: (B) Supercritical to subcritical
Q6Civil · Hydraulics and Environmental EngineeringModerate
Water hammer in pipes is caused by:
Solution
The sudden stop creates a pressure surge.
Answer: (A) Sudden closure of a valve
Q7Civil · Hydraulics and Environmental EngineeringModerate
Solution
It absorbs pressure surges.
Answer: (A) Protect pipelines from water hammer
Q8Civil · Hydraulics and Environmental EngineeringModerate
The duty of water in irrigation is:
Solution
Usually in hectares per cumec.
Answer: (C) The area irrigated per unit discharge
Q9Civil · Hydraulics and Environmental EngineeringModerate
Delta (Δ) in irrigation means:
Solution
Usually expressed in cm or m.
Answer: (B) Total depth of water required by a crop
Q10Civil · Hydraulics and Environmental EngineeringModerate
Evapotranspiration is the combined loss of water by:
Solution
It is the consumptive use of water.
Answer: (D) Evaporation and transpiration by plants
Q11Civil · Hydraulics and Environmental EngineeringModerate
Solution
Rainfall is reported in mm.
Answer: (A) Depth of rainfall
Q12Civil · Hydraulics and Environmental EngineeringModerate
The unit hydrograph represents direct runoff from:
Solution
It is the response to 1 cm (or 1 mm) of effective rain.
Answer: (A) One unit depth of effective rainfall over a given duration
Q13Civil · Hydraulics and Environmental EngineeringModerate
Turbidity in water is caused by:
Solution
It is measured in NTU.
Answer: (D) Suspended particles
Q14Civil · Hydraulics and Environmental EngineeringModerate
Temporary hardness of water is caused by:
Solution
It can be removed by boiling.
Answer: (D) Bicarbonates of calcium and magnesium
Q15Civil · Hydraulics and Environmental EngineeringModerate
Chlorination of water is done for:
Solution
Chlorine kills pathogens.
Answer: (A) Disinfection
Q16Civil · Hydraulics and Environmental EngineeringModerate
BOD of waste water measures:
Solution
Higher BOD means more organic pollution.
Answer: (C) Oxygen needed by microbes to decompose organic matter
Q17Civil · Hydraulics and Environmental EngineeringModerate
The pH of pure water at 25 °C is:
Solution
Neutral water has pH 7.
Answer: (D) 7
Q18Civil · Hydraulics and Environmental EngineeringModerate
Sedimentation in water treatment removes:
Solution
Coagulants help finer particles settle.
Answer: (D) Suspended solids that settle by gravity
Q19Civil · Hydraulics and Environmental EngineeringModerate
A weir is mainly used to:
Solution
Discharge is related to the head over the weir crest.
Answer: (B) Measure or control flow in an open channel
Q20Civil · Hydraulics and Environmental EngineeringModerate
The coefficient of discharge of an orifice is the product of:
Solution
Cd = Cc × Cv.
Answer: (A) Coefficient of contraction and coefficient of velocity
PlacementPrep