MCQOPTIONS
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MCQOPTIONS
This section includes 72 Mcqs, each offering curated multiple-choice questions to sharpen your Water Requirements knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Carbonate hardness (mg/l as CaCO |
| A. | 205 |
| B. | 250 |
| C. | 275 |
| D. | 289 |
| Answer» E. | |
| 52. |
Total hardness (mg/l as CaCO |
| A. | 205 |
| B. | 250 |
| C. | 275 |
| D. | 308 |
| Answer» D. 308 | |
| 53. |
Alkalinity present in the water in mg/l as CaCO |
| A. | 250 |
| B. | 1500 |
| C. | 1750 |
| D. | 5000 |
| Answer» D. 5000 | |
| 54. |
Ultimate BOD of a river water sample is 20 mg/L. BOD rate constant (natural log) is 0.15 day |
| A. | 45 and 55 |
| B. | 55 and 45 |
| C. | 65 and 35 |
| D. | 75 and 25 |
| Answer» D. 75 and 25 | |
| 55. |
A waste water stream (flow = 2m /s, ultimate BOD = 90 mg/l) is joining a small river (flow = 12 m /s, ultimate BOD = 5 mg/ l). Both water streams get mixed up instantaneously. Crosssectional area of the river is 50 m . Assuming the deoxygenation rate constant, k = 0.25.day, the BOD (in mg/l) of the river water, 10 km downstream of the mixing point is |
| A. | 1.68 |
| B. | 12.63 |
| C. | 15.46 |
| D. | 1.37 |
| Answer» D. 1.37 | |
| 56. |
16 MLD of water is flowing through a 2.5 km long pipe of diameter 45 cm. The chlorine at the rate of 32 kg/d is applied at the entry of this pipe so that disinfected water is obtained at the exit. There is a proposal to increase the flow through this pipe to 22 MLD from 16 MLD. Assume the dilution coefficient, n = 1. The minimum amount of chlorine (in kg per day) to be applied to achieve the same degree of disinfection for the enhanced flow is |
| A. | 60.50 |
| B. | 44.00 |
| C. | 38.00 |
| D. | 23.27 |
| Answer» B. 44.00 | |
| 57. |
Consider the following unit processes commonly used in water treatment; rapid mixing (RM), flocculation (F), primary sedimentation (PS), secondary sedimentation (SS), chlorination (C) and rapid sand filteration (RSF). The order of these unit processes (first to last) in a conventional water treatment plant is |
| A. | PS RSF F RM SS C |
| B. | PS F RM RSF SS C |
| C. | PS F SS RSF RM C |
| D. | PS RM F SS RSF C |
| Answer» E. | |
| 58. |
The disinfection efficiency of chlorine in water treatment. |
| A. | is not dependent on pH value. |
| B. | is increase by increased pH value. |
| C. | remains constant at all pH value. |
| D. | is reduced by increased pH value. |
| Answer» E. | |
| 59. |
Most of turbidity meters work on the scattering principle. The turbidity value so obtained is expressed in |
| A. | CFU |
| B. | FTU |
| C. | JTU |
| D. | NTU |
| Answer» E. | |
| 60. |
A water treatment plant is designed to treat 1 m /s of raw water. It has 14 sand filters. Surface area of each filter is 50 m . What is the loading rate (in (m /days.m )) with two filters out of service for routine backwashing? |
| A. | 214 m /day.m |
| B. | 124 m /day.m |
| C. | 174 m /day.m |
| D. | 144 m /day.m |
| Answer» E. | |
| 61. |
What is the surface overflow rate in the sedimentation tank? |
| A. | 20 m /m /day |
| B. | 40 m /m /day |
| C. | 67 m /m /day |
| D. | 133 m /m /day |
| Answer» B. 40 m /m /day | |
| 62. |
The non-carbonate hardness of the sample in mg/l as CaCO |
| A. | 225 |
| B. | 156 |
| C. | 86 |
| D. | 0 |
| Answer» C. 86 | |
| 63. |
The total hardness of the sample in mg/l as CaCO |
| A. | 484 |
| B. | 450 |
| C. | 242 |
| D. | 225 |
| Answer» E. | |
| 64. |
A student began experiment for determination of 5-day, 20 C BOD on Monday. Since the 5 |
| A. | 129 mg/L |
| B. | 127 mg/L |
| C. | 128.0979 mg/L |
| D. | 128 mg/L |
| Answer» D. 128 mg/L | |
| 65. |
A surface water treatment plant operates round the clock with a flow rate of 35 m /min. The water temperature is 15 C and jar testing indicated an alum dosage of 25 mg/l with flocculation at a Gt value of 4 10 |
| A. | 37800 kg |
| B. | 35600 kg |
| C. | 32800 kg |
| D. | 3240 kg |
| Answer» B. 35600 kg | |
| 66. |
A suspension of sand like particles in water with particles of diameter 0.10 mm and below is flowing into a setting tank at 0.10 m /s. Assume g = 9.81 m/s , specific gravity of particles = 2.65, and kinematic viscosity of water = 1.0105 10 |
| A. | 31.09 m |
| B. | 32 m |
| C. | 31.21 m |
| D. | 30 m |
| Answer» D. 30 m | |
| 67. |
A straight 100 m long raw water gravity main is to carry water from an intake structure to the jack well of a water treatment plant. The required flow through this water main is 0.21 m /s. Allowable velocity through the main is 0.75 m/s. Assume f = 0.01, g = 9.81 m/s . The minimum gradient (in cm/100 m length) to be given to this gravity main so that the required amount of water flows without any difficulty is __________. |
| A. | 4.8 cm |
| B. | 4.01 cm |
| C. | 5.8 cm |
| D. | 3.025 cm |
| Answer» B. 4.01 cm | |
| 68. |
A water treatment plant of capacity, 1 m /s has filter boxes of dimensions 6 m 10 m. Loading rate to the filters is 120 m /day/m . When two of the filters are out of service for back washing, the loading rate (in m /day/m ) is |
| A. | 144 m /d/m |
| B. | 147 m /d/m |
| C. | 146 m /d/m |
| D. | 145 m /d/m |
| Answer» B. 147 m /d/m | |
| 69. |
A groundwater sample was found to contain 500 mg/L total dissolved solids (TDS). TDS (in%) present in the sample is ____ |
| A. | 1.75% |
| B. | 0.05% |
| C. | 1.05% |
| D. | 1.25% |
| Answer» C. 1.05% | |
| 70. |
In a wastewater treatment plant, primary sedimentation tank (PST) designed at an overflow rate of 32.5 m /day/m is 32.5 m long, 8.0 m wide and liquid depth of 2.25 m. If the length of the weir is 75 m, the weir loading rate (in m /day/m) is |
| A. | 111.67 m /d/m |
| B. | 110.67 m /d/m |
| C. | 109.67 m /d/m |
| D. | 112.67 m /d/m |
| Answer» E. | |
| 71. |
An effluent at a flow rate of 2670 m /d from a sewage treatment plant is to be disinfected. The laboratory data of disinfection studies with a chlorine dosage of 15 mg/l yield the model Nt = No e 0.145t where Nt = number of microorganisms surviving at time t (in min.) and No = number of micro-organisms present initially (at t = 0). The volume of disinfection unit (in m ) required to achieve a 98% kill of micro-organisms is _______ |
| A. | 55 m |
| B. | 52 m |
| C. | 53 m |
| D. | 50 m |
| Answer» E. | |
| 72. |
Consider a primary sedimentation tank (PST) in a water treatment plant with Surface Overflow Rate (SOR) of 40 m /m /d. The diameter of the spherical particle which will have 90 percent theoretical removal efficiency in this tank is ________ mm. Assume that settling velocity of the particles in water is described by stokes s Law. Given: Density of water = 1000 kg/m ; density of particle = 2650 kg/m ; g = 9.81 m/s ; Kinematic viscosity of water (v) = 1.10 10 |
| A. | 20.58 m |
| B. | 21.58 m |
| C. | 23.58 m |
| D. | 22.58 m |
| Answer» E. | |