MCQOPTIONS
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MCQOPTIONS
This section includes 118 Mcqs, each offering curated multiple-choice questions to sharpen your Waste Water Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
In rapid sand filters, the depth of tank varies in between |
| A. | 1 m to 2 m |
| B. | 2.5 m to 3.5 m |
| C. | 3 m to 3.5 m |
| D. | 0.6 m to 0.9 m |
| Answer» C. 3 m to 3.5 m | |
| 52. |
Analysis of a water sample revealed that the sample contains the following species.\(CO_3^{2 - },\;N{a^ + },\;{H^ + },\;PO_4^3,\;A{l^{3 + }},\;{H_2}C{O_3},\;C{l^2},\;C{a^{2 + }},\;M{g^{2 + }},\;HCO_3^ - ,\;F{e^{2 + }},\;O{H^ - }\)Concentrations of which of the species will be required to compute alkalinity? |
| A. | \(CO_3^{2 - },\;{H^ + },\;HCO_3^ - ,\;O{H^ - }\) |
| B. | \({H^ + },\;{H_2}C{O_3},\;HCO_3^ - ,\;O{H^ - }\) |
| C. | \(CO_3^{2 - },\;{H_2}C{O_3},\;HCO_3^ - ,\;O{H^ - }\) |
| D. | \(CO_3^{2 - },\;{H^ + },\;{H_2}C{O_3},\;HCO_3^ -\) |
| Answer» B. \({H^ + },\;{H_2}C{O_3},\;HCO_3^ - ,\;O{H^ - }\) | |
| 53. |
Disappearance of pink colour of water of a well due to addition of KMnO4 indicates that water contained |
| A. | Acidity |
| B. | Alkalinity |
| C. | Turbidity |
| D. | Organic matter |
| Answer» E. | |
| 54. |
Alkalinity in water is expressed as milligrams per litre in terms of equivalent: |
| A. | Calcium hydroxide |
| B. | Sodium carbonate |
| C. | Magnesium carbonate |
| D. | Calcium carbonate |
| Answer» E. | |
| 55. |
A sedimentation tank removes 210 kg of suspended solids per day. What will be the volume of sludge produced per day if the moisture content of sludge is 95% (by weight) and specific gravity of wet sludge is 1.05? |
| A. | 5 m3 |
| B. | 10 m3 |
| C. | 30 m3 |
| D. | 20 m3 |
| Answer» B. 10 m3 | |
| 56. |
Alum as a coagulant is found to be effective between pH range of________ |
| A. | 8.0 to 10.0 |
| B. | 8.5 to 10.5 |
| C. | 6.5 to 8.5 |
| D. | 7.0 to 9.0 |
| Answer» D. 7.0 to 9.0 | |
| 57. |
A good disinfectant1. Should be persistent enough to prevent regrowth of organisms in the distribution system.2. Must be toxic to micro-organisms at concentrations well above the toxic thresholds of humans and higher animals.3. Should have a fast rate of kill of micro-organisms.Select the correct answer using the codes given below: |
| A. | 1, 2 and 3 |
| B. | 1 and 2 only |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» D. 2 and 3 only | |
| 58. |
An experiment shows that a concentration of 0.1 g/m3 of free available chlorine yield a 99% kill of bacteria in 8 minutes. Calculate disinfection rate constant (1 /min)? Assume that Chick's Law and Watson's Law hold with n = 1. |
| A. | 0.4706 /min |
| B. | 0.2056 /min |
| C. | 0.7056 /min |
| D. | 0.5756 /min |
| Answer» E. | |
| 59. |
Consider the following statements regarding the overflow rate of a sedimentation tank1. Temperature of water affects the overflow rate2. Size of particle intended to be removed does not affect the overflow rate3. Density of particle intended to be removed affects the overflow rateWhich of the above statements are correct? |
| A. | 1 and 3 only |
| B. | 1 and 2 only |
| C. | 2 and 3 only |
| D. | 1, 2 and 3 |
| Answer» B. 1 and 2 only | |
| 60. |
Calculate detention time of the tank whose breadth is 2 m, length is 4 m and depth is 2.5 m. The rate of flow is 4 × 103 liters per hour. |
| A. | 5 hours |
| B. | 4 hours |
| C. | 5.5 hours |
| D. | 2.5 hours |
| Answer» B. 4 hours | |
| 61. |
How much bleaching powder (having 20% available chlorine) is needed to disinfect 10,000 litres of water whose chlorine demand is 1.0 mg/l? It should be ensured that, after about 1 hour contact time, 0.2 mg/l chlorine is available. |
| A. | 30 g |
| B. | 40 g |
| C. | 48 g |
| D. | 68 g |
| Answer» E. | |
| 62. |
A water supply scheme transports 10 MLD (Million Litres per Day) water through a 450 mm diameter pipeline for a distance of 2.5 km. A chlorine dose of 3.50 mg/litre is applied at the starting point of the pipeline to attain a certain level of disinfection at the downstream end. It is decided to increase the flow rate from 10 MLD to 13 MLD in the pipeline. Assume exponent for concentration, n = 0.86. With this increased flow, to attain the same level of disinfection, the chlorine dose (in mg/litre) to be applied at the starting point should be |
| A. | 3.95 |
| B. | 4.40 |
| C. | 4.75 |
| D. | 5.55 |
| Answer» D. 5.55 | |
| 63. |
If W is total BOD, V is filter volume and F is recirculation factor in a trickling filter, then unit organic loading is obtained by |
| A. | \(u = \frac{{WF}}{V}\) |
| B. | \(u = \frac{{VF}}{W}\) |
| C. | \(u = \frac{{WV}}{F}\) |
| D. | \(u = \frac{{W}}{VF}\) |
| Answer» E. | |
| 64. |
As per IS 10500, the maximum allowable concentration of flurodies in drinking water is: |
| A. | 1.50 mg/l |
| B. | 9.10 mg/l |
| C. | 4.50 mg/l |
| D. | 11.30 mg/l |
| E. | 15.00 mg/l |
| Answer» B. 9.10 mg/l | |
| 65. |
Cleaning is done by(i) Scraping and removal of top layer in slow sand filter;(ii) Back washing in slow sand filters;(iii) Scraping and removal of top layer in rapid sand filter;(iv) Back washing in rapid sand filters.The correct answer is |
| A. | (i) and (iv) |
| B. | (ii) and (iii) |
| C. | (ii) and (iv) |
| D. | (i) and (iii) |
| Answer» B. (ii) and (iii) | |
| 66. |
Identify coagulant with highest power for coagulating positive colloids: FeCl3; Na3SO4; C6H12O6; Na3PO4 |
| A. | FeCl3 |
| B. | Na3SO4 |
| C. | C6H12O6 |
| D. | Na3PO4 |
| Answer» E. | |
| 67. |
Boiling of water or adding lime in water will remove the hardness of water when it is due to: |
| A. | nitrate of calcium |
| B. | chloride of calcium |
| C. | sulphate of calcium |
| D. | carbonate of calcium |
| Answer» E. | |
| 68. |
Alum as a coagulant is found to be most effective when the pH range of water is |
| A. | 2 to 4 |
| B. | 4 to 6 |
| C. | 6 to 8 |
| D. | 8 to 10 |
| Answer» D. 8 to 10 | |
| 69. |
One Nephelometry Turbidity Unit (NTU) is equal to the turbidity produced by: |
| A. | 1 mg SiO2 dissolved in 1l of distilled water with the test being run according to absorption principle |
| B. | 1 mg SiO2 dissolved in 1l of distilled water with the test being run according to scattering principle. |
| C. | 1 mg Formazin dissolved in 1l of distilled water with the test being run according to absorption principle. |
| D. | 1 mg Formazin dissolved in 1l of distilled water with the test being run according to scattering principle. |
| Answer» E. | |
| 70. |
According to Terzaghi and peck, the ratio of D15 size of filter material to the D85 size of the base material should be: |
| A. | < 10 |
| B. | < 4 |
| C. | < 25 |
| D. | < 15 |
| Answer» C. < 25 | |
| 71. |
Inhibitors are used along with sanitizer to |
| A. | improve their action |
| B. | to prevent corrosion |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» C. both (a) and (b) | |
| 72. |
Permanent hardness of water is caused by the presence of |
| A. | bicarbonates of calcium and magnesium |
| B. | carbonates of sodium and potassium |
| C. | chlorides and sulfates of calcium and magnesium |
| D. | phosphates of sodium and potassium |
| Answer» D. phosphates of sodium and potassium | |
| 73. |
Which of the following chemical is sometime added in the process of coagulation and flocculation? |
| A. | Aluminum sulphate |
| B. | Aluminum oxide |
| C. | Calcium chloride |
| D. | None of these |
| Answer» B. Aluminum oxide | |
| 74. |
Temporary hardness of water is caused by the presence of |
| A. | chlorides of calcium and magnesium |
| B. | sulfates of calcium and magnesium |
| C. | bicarbonates of calcium and magnesium |
| D. | carbonates of sodium and potassium |
| Answer» D. carbonates of sodium and potassium | |
| 75. |
Sedimentation is a physical process used in wastewater treatment to |
| A. | remove particles that are less dense than water |
| B. | remove particles that are more dense than water |
| C. | remove the pertinacious material from the water |
| D. | none of the above |
| Answer» C. remove the pertinacious material from the water | |
| 76. |
Application of quaternary ammonium compounds as sanitizing agents tends to |
| A. | favor gram positive bacteria |
| B. | decrease gram positive bacteria |
| C. | increase the percentage of gram(-)ve rods on utensils |
| D. | none of the above |
| Answer» D. none of the above | |
| 77. |
Acid used mostly for removal of milk stone is |
| A. | phosphoric acid |
| B. | nitric acid |
| C. | gluconic acid |
| D. | tartaric acid |
| Answer» C. gluconic acid | |
| 78. |
The methods used for biological treatment are |
| A. | lagoon |
| B. | activated sludge process |
| C. | oxidation ditches |
| D. | all of these |
| Answer» E. | |
| 79. |
Both temporary and permanent hardness of water can be removed by |
| A. | boiling |
| B. | distillation |
| C. | filtration |
| D. | decantation |
| Answer» C. filtration | |
| 80. |
Both temporary and permanent hardness of water can be removed on boiling water with |
| A. | calcium hydroxide |
| B. | sodium carbonate |
| C. | calcium oxide |
| D. | calcium carbonate |
| Answer» C. calcium oxide | |
| 81. |
Secondary treatment uses __________ to consume wastes. |
| A. | micro-organisms |
| B. | chemicals |
| C. | filtration |
| D. | none of these |
| Answer» B. chemicals | |
| 82. |
The activated sludge process consists of returning a portion of the clarifier |
| A. | effluent water entering the reactor |
| B. | influent water coming out of the reactor |
| C. | influent water entering the reactor |
| D. | effluent water coming out of the reactor |
| Answer» D. effluent water coming out of the reactor | |
| 83. |
Sanitizer used specifically for vitreous enamel are |
| A. | strong alkalis |
| B. | strong acids |
| C. | weak alkali with sodium silicate |
| D. | none of these |
| Answer» D. none of these | |
| 84. |
Hardness of water does not |
| A. | have any bad effect in boiler |
| B. | make cooking of foods difficult |
| C. | make it unfit for drinking |
| D. | cause difficulty in the washing of clothes with soaps |
| Answer» D. cause difficulty in the washing of clothes with soaps | |
| 85. |
The common methods used for disinfection in waste water treatment plants are |
| A. | chlorination |
| B. | UV light |
| C. | both (a) and (b) |
| D. | Phenolic solvent |
| Answer» D. Phenolic solvent | |
| 86. |
Permanent hard water may be softened by passing it through |
| A. | sodium silicate |
| B. | sodium bicarbonate |
| C. | sodium hexametaphosphate |
| D. | sodium phosphate |
| Answer» D. sodium phosphate | |
| 87. |
Coliform bacteria in water is an indication of the presence of |
| A. | radioactive wastes |
| B. | excess fertilizer |
| C. | decaying animals and plants |
| D. | human feces |
| Answer» E. | |
| 88. |
Biological oxidation processes usually referred as biological treatment, are the most common form of |
| A. | primary treatment |
| B. | secondary treatment |
| C. | tertiary treatment |
| D. | all of these |
| Answer» C. tertiary treatment | |
| 89. |
Temporary hardness of water may be removed by adding |
| A. | calcium hydroxide |
| B. | calcium carbonate |
| C. | calcium chloride |
| D. | sodium bicarbonate |
| Answer» B. calcium carbonate | |
| 90. |
The maximum permissible limit (BIS) of turbidity in drinking water is |
| A. | 5 NTU |
| B. | 10 NTU |
| C. | 15 NTU |
| D. | 20 NTU |
| Answer» C. 15 NTU | |
| 91. |
Zeolite used in zeolite softening process for the treatment of hard water gets exhausted after certain time of usage but can be regenerated by flushing it with |
| A. | 10% calcium chloride solution |
| B. | 10% magnesium sulfate solution |
| C. | 10% magnesium chloride solution |
| D. | 10% sodium chloride solution |
| Answer» E. | |
| 92. |
Lagoons may be characterized as |
| A. | anaerobic |
| B. | facultative |
| C. | aerated |
| D. | all of these |
| Answer» E. | |
| 93. |
From the following sanitizers which one comes under category of surface active agents? |
| A. | Tetra phosphate |
| B. | Teepol |
| C. | Meta phosphate |
| D. | None of these |
| Answer» C. Meta phosphate | |
| 94. |
The maximum desirable limit (BIS of mercury in the drinking water is |
| A. | 0.05 mg/l |
| B. | 0.9 mg/l |
| C. | 0.1 mg/l |
| D. | 0.001 mg/l |
| Answer» E. | |
| 95. |
The activated sludge process is sometime referred as |
| A. | fluid bed biological oxidation system |
| B. | fixed bed biological oxidation system |
| C. | turning bed biological oxidation system |
| D. | none of the above |
| Answer» B. fixed bed biological oxidation system | |
| 96. |
Calgon is used for removal of |
| A. | sodium carbonate |
| B. | permanent hardness of water |
| C. | potassium carbonate |
| D. | none of these |
| Answer» C. potassium carbonate | |
| 97. |
The ultimate source of water is |
| A. | rivers and lakes |
| B. | dew and forest |
| C. | rain and snow |
| D. | underground and surface |
| Answer» D. underground and surface | |
| 98. |
When temporary hard water is boiled, one of the substances formed is |
| A. | calcium bicarbonate |
| B. | calcium sulfate |
| C. | hydrogen chloride |
| D. | carbon dioxide |
| Answer» E. | |
| 99. |
The purest form of naturally occurring water is |
| A. | rain water |
| B. | river water |
| C. | pond water |
| D. | well water |
| Answer» B. river water | |
| 100. |
The water being used in dairy industry should contain not more than |
| A. | 5 proteolytic and/or lipolytic organisms per ml |
| B. | 10 proteolytic and/or lipolytic organisms per ml |
| C. | 15 proteolytic and/or lipolytic organisms per ml |
| D. | 20 proteolytic and/or lipolytic organisms/ml |
| Answer» B. 10 proteolytic and/or lipolytic organisms per ml | |