All Free Civil Engineering MCQs with Answers

• A. Equally and undiminished in all directions
• B. Only vertically through the fluid
• C. Only along the piston movement
• D. With increasing pressure at greater depth

Explanation: Pascal's law states that an applied pressure is transmitted undiminished throughout a confined fluid.

• A. Between about 2,000 and 4,000
• B. Less than about 2,000
• C. Greater than about 4,000
• D. Equal to the Froude number

Explanation: For flow in a circular pipe, Reynolds numbers below about 2,000 normally indicate laminar flow.

• A. An increase in fluid viscosity to zero
• B. A reduction in atmospheric pressure
• C. Boundary-layer separation and eddies
• D. Conversion of all pressure head into velocity head

Explanation: A sudden enlargement causes flow separation and eddy formation, which dissipate mechanical energy as turbulence.

• A. Q = A R S n
• B. Q = n A R^(2/3) S^(1/2)
• C. Q = (1/n) A R^(1/2) S^(2/3)
• D. Q = (1/n) A R^(2/3) S^(1/2)

Explanation: The Manning equation is Q = (1/n) A R^(2/3) S^(1/2), where n is roughness, A is flow area, R is hydraulic radius, and S is energy slope.

• A. Pelton turbine
• B. Kaplan turbine
• C. Propeller turbine
• D. Cross-flow turbine

Explanation: A Pelton turbine is an impulse turbine designed for high-head, low-discharge conditions.

• A. Depth of water applied to a field
• B. Area irrigated by unit discharge during the base period
• C. Time required to convey water to a field
• D. Discharge needed to remove excess soil moisture

Explanation: Duty is the area irrigated by one unit of discharge throughout the crop base period, commonly expressed in hectares per cumec.

• A. Evaporation exceeds precipitation for a season
• B. Groundwater level falls below the stream bed
• C. Rainfall intensity exceeds the soil's infiltration capacity
• D. The soil absorbs all rainfall without storage

Explanation: When rainfall intensity is greater than the rate at which soil can absorb water, the excess flows over the surface.

• A. 0.5 percent
• B. 2 percent
• C. 5 percent
• D. 50 percent

Explanation: For an event with return period T, the annual exceedance probability is approximately 1/T.

• A. Reduce fluctuation in discharge and power requirement
• B. Increase the water's density
• C. Convert pressure energy into turbine shaft power
• D. Prevent all pipe friction losses

Explanation: An air vessel stores and releases water during the pumping cycle, making discharge more uniform and reducing acceleration effects and…

• A. Specific weight
• B. Density
• C. Specific gravity
• D. Bulk modulus

Explanation: Kinematic viscosity is ν = μ/ρ, where μ is dynamic viscosity and ρ is density.

• A. Friction head
• B. Velocity head
• C. Pressure head
• D. Datum head

Explanation: The hydraulic grade line is given by z + p/γ, so it combines elevation head and pressure head.

• A. Zero at each junction
• B. Greater in the smallest pipe
• C. Greater in the largest pipe
• D. The same in every pipe

Explanation: Continuity requires the same discharge through each pipe in a series arrangement.

• A. Vapour pressure
• B. Atmospheric pressure
• C. Stagnation pressure
• D. Critical pressure

Explanation: Cavitation occurs when local absolute pressure becomes less than the liquid vapour pressure, causing vapour bubbles to form.

• A. Water surface
• B. Channel bed
• C. Top of the bank
• D. Hydraulic grade line

Explanation: Specific energy is the energy per unit weight measured with the channel bed as the datum, expressed as E = y + V²/(2g).

• A. Propeller turbine
• B. Pelton turbine
• C. Francis turbine
• D. Cross-flow turbine

Explanation: The Francis turbine is a reaction turbine commonly used for medium heads and medium discharges.

• A. Surcharge storage
• B. Live storage
• C. Flood storage
• D. Dead storage

Explanation: Dead storage lies below the lowest outlet and normally cannot be released by gravity through that outlet.

• A. Rainfall intensity
• B. Reservoir capacity
• C. Channel roughness only
• D. Groundwater table depth

Explanation: The Rational Method uses Q = CIA, so peak discharge is proportional to rainfall intensity, runoff coefficient, and drainage area.

• A. All soil pores contain air
• B. Excess gravitational water has drained
• C. The soil reaches permanent wilting
• D. The crop has used all available water

Explanation: Field capacity is approximately the water content after free gravitational drainage has largely stopped.

• A. It decreases linearly with depth
• B. It remains constant with depth
• C. It increases linearly with depth
• D. It increases exponentially with depth

Explanation: Hydrostatic pressure increases linearly with depth because the liquid above the point contributes a greater weight.

• A. Top width to flow depth
• B. Wetted perimeter to flow area
• C. Flow area to top width
• D. Flow area to wetted perimeter

Explanation: Hydraulic radius is R = A/P, where A is the cross-sectional flow area and P is the wetted perimeter.