civil engineering Mcqs
4451. The detention period in coagulation tanks is usually kept as_______________?
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A. 2 to 6 hours

B. 1 to 2 minutes

C. 2 to 6 days

D. 30 to 45 minutes

4452. Most suitable section of sewer in separate sewage system is________________?
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A. rectangular section

B. circular section

C. modified egg shaped section

D. standard form of egg shaped sewer

4453. The gas from sludge digestion tank is mainly composed of __________________?
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A. nitrogen

B. methane

C. hydrogen sulphide

D. carbon dioxide

4454. The means of access for inspection and cleaning of sewer line is known as_______________?
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A. catch basin

B. drop manhole

C. manhole

D. inlet

4455. Scour valves are provided ______________?
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A. at the foot of rising main along the slope to prevent back running of water

B. at every summit of rising mains

C. at street corners to control the flow of water

D. at every depression and dead ends to drain out the waste water that may collect there
4456. The phenolic compounds in public water supply should not be more than_______________?
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A. 0.1 ppm

B. 0.01 ppm

C. 0.001 ppm

D. 0.0001 ppm

4457. The self cleansing velocity for all sewers in India is usually_________________?
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A. 1.5 m/sec to 2.0 m/sec

B. 3.0 m/sec to 3.5 m/sec

C. less than 1.0 m/sec

D. 1.0 m/sec to 1.2 m/sec
4458. The settling velocity of a particle in a sedimentation tank increases if______________?
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A. the depth of tank is decreased

B. particle size is decreased

C. none of the above

D. the surface area of tank is increased

4459. The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is______________?
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A. 4 ppm

B. 10 ppm

C. 40 ppm

D. 1 ppm

4460. For a given discharge, the efficiency of sedimentation tank can be increased by______________?
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A. increasing the depth of tank

B. increasing the surface area of tank

C. decreasing the surface area of tank

D. decreasing the depth of tank

4461. Period of cleaning of slow sand filters is about________________?
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A. 2-3 months

B. 24 48 hours

C. 1-2 year

D. 10-12 days

4462. Sludge volume index is defined as the ratio of_______________?
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A. percentage of sludge by volume to percentage of total solids by weight

B. percentage of total solids by weight to percentage of sludge by volume

C. percentage of suspended solids by weight to percentage of sludge by volume

D. percentage of sludge by volume to percentage of suspended solids by weight
4463. Which of the following values of pH represents a stronger acid?
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A. 2

B. 5

C. 10

D. 7

4464. The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is______________?
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A. zero

B. 1

C. infinite

D. 100
4465. Which of the following is not a water borne disease ?
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A. typhoid

B. maleria

C. dysentery

D. cholera

4466. Assertion A : The consumption of water increases with increase in the distribution pressure. Reason R : Higher distribution pressure causes more loss and waste of water. Select your answer according to the coding system given below?
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A. Both A and R are true and R is the correct explanation of A

B. Both A and R are true but R is not the correct explanation of A

C. A is true but R is false

D. A is false but R is true

4467. An egg shaped section of sewer________________?
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A. is more stable than circular section

B. is economical than circular section

C. is easy to construct

D. provides self cleansing velocity at low discharges
4468. In a BOD test, 1.0 ml of raw sewage was diluted to 100 ml and the dissolved oxygen concentration of diluted sample at the beginning was 6 ppm and it was 4 ppm at the end of 5 day incubation at 20C. The BOD of raw sewage will be___________?
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A. 400 ppm

B. 100 ppm

C. 200 ppm

D. 300 ppm

4469. The population of a town in three consecutive years are 5000, 7000 and 8400 respectively. The population of the town in the fourth consecutive year according to geometrical increase method is________________?
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A. 9500

B. 9800

C. 10920

D. 10100

4470. The design discharge for the separate sewer system shall be taken as_____________?
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A. 3 x DWF

B. equal to dry weather flow (DWF)

C. 6xDWF

D. 2xDWF

4471. The type of valve which is provided to control the flow of water in the distribution system at street corners and where the pipe lines intersect is_______________?
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A. sluice valve

B. check valve

C. safety valve

D. scour valve

4472. If Biochemical oxygen demand (BOD. of a town is 20000 kg/day and BOD per capita per day is 0.05 kg, then population equivalent of town is_________________?
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A. 100000

B. 1000

C. 400000

D. 4000

4473. Air binding phenomena in rapid sand filters occur due to_________________?
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A. higher turbidity in the effluent

B. excessive negative head

C. low temperature

D. mud ball formation

4474. For normal sludge, the value of sludge index for Indian conditions is________________?
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A. 150 to 350

B. 50 to 150

C. 0 to 50

D. 350 to 500

4475. In water treatment, rapid gravity filters are adopted to remove_______________?
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A. dissolved organic substances

B. dissolved solids and dissolved gases

C. bacteria and colloidal solids

D. floating solids and dissolved inorganic solids

4476. The layout of distribution system in which water flows towards the outer periphery is_________________?
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A. radial system

B. ring system

C. dead end system

D. grid iron system

4477. For satisfactory working of a sludge digestion unit, the pH range of digested sludge should be maintained as___________________?
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A. 10.5 to 12.0

B. 8.5 to 10.0

C. 4.5 to 6.0

D. 6.5 to 8.0
4478. The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally_______________?
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A. more and less

B. more and more

C. less and more

D. less and less

4479. Which of the following chemical compounds can be used for dechlorination of water ?
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A. chloramines

B. carbon dioxide

C. sulphur dioxide

D. bleaching powder

4480. The effect of increasing diameter of sewer on the self cleansing velocity is_____________?
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A. fluctuating

B. to decrease it

C. to increase it

D. nil

4481. The detention period for oxidation ponds is usually kept as______________?
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A. 24 hours

B. 4-8 hours

C. 3 months

D. 10 to 15 days
4482. Alkalinity in water is expressed as milli-grams per litre in terms of equivalent_______________?
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A. calcium carbonate

B. calcium hydroxide

C. sodium carbonate

D. magnesium carbonate

4483. If the sewage contains grease and fatty oils, these are removed in_________________?
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A. grit chambers

B. sedimentation tanks

C. skimming tanks

D. detritus tanks

4484. Which of the following sewers is preferred for combined system of sewage ?
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A. none of the above

B. circular sewer

C. rectangular sewer

D. egg shaped sewer
4485. The maximum permissible size of aggregates to be used in casting the ribs of a slab, is______________?
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A. 10 mm

B. 7.5 mm

C. 5 mm

D. 15 mm

4486. Columns may be made of plain concrete if their unsupported lengths do not exceed their least lateral dimension_______________?
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A. Two times

B. Three times

C. Four times

D. Five times

4487. If R and T are rise and tread of a stair spanning horizontally, the steps are supported by a wall on one side and by a stringer beam on the other side, the steps are designed as beams of width_______________?
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A. R + T

B. 2 + T2)

C. T R

D. R T

4488. A pre-stressed rectangular beam which carries two concentrated loads W at L/3 from either end, is provided with a bent tendon with tension P such that central one-third portion of the tendon remains parallel to the longitudinal axis, the maximum dip h is_____________________?
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A. WL/P

B. WL/2P

C. WL/4P

D. WL/3P
4489. If C is creep coefficient, f is original pre-stress in concrete, m is modular ratio, E is Youngs modulus of steel and e is shrinkage strain, the combined effect of creep and shrinkage is________________?
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A. (1 C)mf + eE

B. (1 C) mf eE

C. (C 1)mf eE

D. (C 1)mf + eE
4490. High strength concrete is used in pre-stressed member________________?
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A. To provide high bond stresses

B. All the above

C. To overcome high bearing stresses developed at the ends

D. To overcome bursting stresses at the ends

4491. Top bars are extended to the projecting parts of the combined footing of two columns Ldistance apart for a distance of_______________?
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A. 0.1 L from the outer edge of column

B. One -fourth the distance of projection

C. 0.1 L from the centre edge of column

D. Half the distance of projection

4492. The design of heel slab of a retaining wall is based on the maximum bending moment due to______________?
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A. Its own weight

B. Load of the surcharge, if any

C. Weight of the soil above it

D. All the above
4493. Enlarged head of a supporting column of a flat slab is technically known as______________?
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A. Drop panel

B. Supporting end of the column

C. Capital

D. Top of the column

4494. The transverse reinforcements provided at right angles to the main reinforcement_______________?
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A. All the above

B. Resist the temperature stresses

C. Distribute the load

D. Resist the shrinkage stress

4495. If A is the area of the foundation of a retaining wall carrying a load W and retaining earth of weight w per unit volume, the minimum depth (h) of the foundation from the free surface of the earth, is )/(1 + sin )]_________________?
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A. h = (W/Aw) [(1 )/(1 + sin )]

B. h W/Aw) [(1 )/(1 + sin )]

C. h = (W/Aw) [(1 + )/(1 + sin )]

D. h = (W/Aw) [(1

4496. If the tendon is placed at an rectangular beam (sectional top edge)________________?
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A. Is decreased by Pe/Z

B. Is increased by Pe/Z

C. Is increased by PZ/e

D. Remains unchanged

4497. If the bearing capacity of soil is 10 tonnes/cm2 and the projection of plain concrete footing from walls, is a cm, the depth D of footing is_______________?
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A. D = 0.775 a

B. D = 0.775 a

C. D = 0.0775 a

D. D = 0.775 a2

4498. The self-weight of the footing, is_____________?
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A. Not considered for calculating the upward pressure on footing

B. Also considered for calculating the upward pressure on footing

C. Not considered for calculating the area of the footing

D. Both B. and C

4499. The neutral axis of a T-beam exists_________________?
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A. Below the slab

B. At the bottom edge of the slab

C. All the above

D. Within the flange

4500. A pre-cast pile generally used, is______________?
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A. Square

B. Square with corners chamfered

C. Octagonal

D. Circular