Quiz: Civil Engineering

Exam: SSC-JE

Topic: MISCELLANEOUS

Each question carries 1 mark

Negative marking: 1/4 mark

Time: 10 Minutes

Q1. After which of the following treatment units, the turbidity is maximum ?

(a) Chlorination

(b) Primary sedimentation

(c) Flocculation basin

(d) Secondary sedimentation

Q2. The gauge pressure at point ‘A’ in the inclined manometer shown in the given figure is:

(a) 6680 N/m²

(b) –6680 Nm²

(c) 3340 N/m²

(d) –3340 N/m²

Q3. A vertically immersed surface of size b × d has it width b parallel to the water surface and depth of its centroid from the water surface is ¯x . The distance of its centre of water pressure from the water surface is

(a) bd²/12+ ¯x

(b) d²/12+ ¯x

(c) d²/(12¯x)+ ¯x

(d) b²/(12¯x)+¯x

Q4. Given the x-component of the velocity u = 6xy – 2x², the y-component of the flow velocity is given by:

(a) 6y² – 4xy

(b) –6xy + 2x²

(c) 6x² – 2xy

(d) 4xy – 3y²

Q5. Both free vortex and forced vortex can be expressed mathematically in terms of tangential velocity v at the corresponding radius r. Choose the correct combination

Free vortex Forced vortex

(a) v = r = constant vr = constant

(b) v²r = constant v = r constant

(c) vr = constant v² = r constant

(d) vr = constant v = r constant

Q6. Depth-Area-Duration curves of precipitation at a station would normally be

(a) curves, concave upwards, with duration increasing outward

(b) curves, concave downwards, with duration decreasing outward

(c) curves, concave upwards, with duration decreasing outward

(d) curves, concave downwards, with duration decreasing outward

Q7. The sides of a rectangle are (120 ±0.05)m and (180±0.06)m. The probable error in the area will be

(a) ± 16.8 sq m

(b) ± 12.3 sq m

(c) ± 16.2 sq m

(d) ± 11.53 sq m

Q8. If a quantity A has a weight of 3, then the weight of A/3 will be

(a) 28

(b) 27

(c) 24

(d) 21

Q9. The difference between the most probable value of a quantity and its observer value is

(a) true error

(b) weighted observations

(c) conditional error

(d) residual error

Q10. In the prismatic compass

(a) The magnetic needle moves with the box

(b) the line of the sight does not move with the box

(c) the magnetic needle and graduated circle do not move with the box

(d) the graduated circle needle always remains in the N–S direction

SOLUTION

S1. Ans.(c)

Sol. Flocculation basin is used for formation of flocs through coagulation. After this process Turbidity is highest. Primary sedimentation causes setting of particles and Turbidity reduces.

S2. Ans.(d)

Sol. Gauge pressure at point ‘A’ will be negative due to drop in mercury level.

P = – ρ_m g sin 30°

= – 13.6 × 9810 × 0.05 × 1/2

= – 3335.4 N/m^2

S3. Ans.(c)

Sol. Centre of Water Pressure

h ̅ = x ̅ + I_GXY/A_X ̅ I_GXX = (bd^3)/12

h ̅=x ̅+d^2/(12_X ̅ ) A = bd

S4. Ans.(d)

Sol. The flow must satisfy continuity equation.

∂u/∂x+ ∂v/∂y = 0

∂v/∂y = – ∂u/∂x = – (6y – 4x) = 4x – 6y

▭(V=4xy –3y^2 )

S5. Ans.(d)

Sol. For force vortex flow

V = rw

▭(V ∝r)

For free vortext flow

▭(vr=constant)

S6. Ans.(b)

Sol. Depth-area duration curves of precipitation at a station would normally be concave downward with duration decreasing outward.

S7. Ans.(d)

Sol. Error of area is given by

e_A = √((e_i dA/dl)^2+ (e_b dA/db)^2 )

dA/dl = b = 180

dA/db = l = 180

e_A = √((0.05×180)^2+ (0.06×120)^2 )

= √(9^2+ 〖7.2〗^2 )

= 11.53 sq. m.

S8. Ans.(b)

Sol. Weight of quantity A = 3

Weight of quantity A/3 = 3 × 3^2 = 27

S9. Ans.(d)

Sol. The difference between the most probable value of a quantity and its observer value is residual error.

S10. Ans.(c)

Sol. In prismatic compress the magnetic needle and graduated circle do not move with the box.