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.
| 1. |
A student began experiment for determination of 5-day, 20 C BOD on Monday. Since the 5th day fell on Saturday, the final DO readings were taken on next Monday. On calculation, BOD (i.e. 7 day, 20 C) was found to be 150 mg/L. What would be the 5-day, 20 C BOD (in mg/L)? Assume value of BOD rate constant (k) at standard temperature of 20 C as 0.23/day (base e). |
| A. | 129 mg/L |
| B. | 127 mg/L |
| C. | 128.0979 mg/L |
| D. | 128 mg/L |
| Answer» D. 128 mg/L | |
| 2. |
Total hardness in mg/l as CaCO3 is |
| A. | 1500 |
| B. | 2000 |
| C. | 3000 |
| D. | 5000 |
| Answer» C. 3000 | |
| 3. |
The results of analysis of a raw water sample are given below [2003, 1 marks] Turbidity:5 mg/LpH:7.4Fluorides:2.5 mg/LTotal Hardness:300 mg/LIron:3.0 mg/LMPN:50 per 100 mlFrom the data given above, it can be inferred that water needs removal of |
| A. | Turbidity followed by disinfection |
| B. | Fluorides and Hardness |
| C. | Iron, followed by disinfection |
| D. | Both (b) and (c) |
| Answer» D. Both (b) and (c) | |
| 4. |
Chlorine gas used for disinfection combines with water to form hypochlorous acid (HOCl). The HOCl ionizes to form hypochlorite (OCl ) in a reversible reaction: HOCl H+ + OCl (k = 2.7 10 8 at 20 C) the equilibrium of which is governed by pH. the sum of HOCI and OCl is known as free chlorine residual and HOCl is the more effective disinfectant. The 90% fraction of HOCl in the free chlorine residual is available at a pH value. |
| A. | 4.3 |
| B. | 6.6 |
| C. | 7.5 |
| D. | 9.4 |
| Answer» E. | |
| 5. |
A water treatment plant is required to process 28800 m /d of raw water (density = 1000 kg/m , kinematic viscosity = 10 6 m /s). The rapid mixing tank imparts a velocity gradient of 900s 1 to blend 35 mg/l of alum with the flow for a detention time of 2 minutes. The power input (W) required for rapid mixing is |
| A. | 32.4 |
| B. | 36 |
| C. | 324 |
| D. | 32400 |
| Answer» E. | |
| 6. |
Anaerobically treated effluent has MPN of total coliform as 106 /100 ml. After chlorination, the MPN value declines to 10 /100 ml. The per cent removal (%R) and log removal (log R) of total coliform MPN is |
| A. | %R = 99.90; log R = 4 |
| B. | %R = 99.90; log R = 2 |
| C. | %R = 99.99; log R = 4 |
| D. | %R = 99.99; log R = 2 |
| Answer» D. %R = 99.99; log R = 2 | |
| 7. |
The alkalinity and hardness of a water sample are 250 mg/l and 350 mg/l as CaCO3, respectively. The water has |
| A. | 350 mg/l carbonate hardness and zero non-carbonate hardness. |
| B. | 250 mg/l carbonate hardness and zero non-carbonate hardness. |
| C. | 250 mg/l carbonate hardness and 350 mg/l noncarbonate hardness. |
| D. | 250 mg/l carbonate hardness and 100 mg/l noncarbonate hardness. |
| Answer» E. | |
| 8. |
A synthetic sample of water is prepared by adding 100 mg Kaolinite (a clay mineral), 200 mg glucose, 168 mg NaCl, 120 mg MgSO4 and 111 mg CaCl2 to 1 litre of pure water. The concentrations of total solids (TS) and fixed dissolved solids (FDS) respectively in the solution in mg/L are equal to |
| A. | 699 and 599 |
| B. | 599 and 399 |
| C. | 699 and 199 |
| D. | 699 and 399 |
| Answer» B. 599 and 399 | |
| 9. |
Ultimate BOD of a river water sample is 20 mg/L. BOD rate constant (natural log) is 0.15 day-1. The respective values of BOD (in%) exerted and remaining after 7 days are: |
| A. | 45 and 55 |
| B. | 55 and 45 |
| C. | 65 and 35 |
| D. | 75 and 25 |
| Answer» D. 75 and 25 | |
| 10. |
In disinfection, which of the following forms of chlorine is most effective in killing the pathogenic bacteria? |
| A. | Cl |
| B. | OCl |
| C. | NH |
| D. | Cl |
| E. | HOCl |
| Answer» E. HOCl | |
| 11. |
Carbonate hardness (mg/l as CaCO3) present in the above water sample is |
| A. | 205 |
| B. | 250 |
| C. | 275 |
| D. | 289 |
| Answer» E. | |
| 12. |
Total hardness (mg/l as CaCO3) present in the above water sample is |
| A. | 205 |
| B. | 250 |
| C. | 275 |
| D. | 308 |
| Answer» D. 308 | |
| 13. |
Alkalinity present in the water in mg/l as CaCO3 is |
| A. | 250 |
| B. | 1500 |
| C. | 1750 |
| D. | 5000 |
| Answer» D. 5000 | |
| 14. |
Group 1 contains some properties of water/wastewater and group 2 contains list of some tests on water/waste water Match the property with corresponding test. [2005, 2 marks] Group 1Group 2P. Suspended1. BOD solids concentrationQ. Metabolism of biodegradable organics2. MPNR. Bacterial concentration3. Jar testS. Coagulant dose4. Turbidity |
| A. | P 2, Q 1, R 4, S 3 |
| B. | P 4, Q 1, R 2, S 3 |
| C. | P 2, Q 4, R 1, S 3 |
| D. | P 4, Q 2, R 1, S 3 |
| Answer» C. P 2, Q 4, R 1, S 3 | |
| 15. |
Some of the water quality parameters are measured by titrating a water sample with a titrant. Group I gives a list of parameters and Group II gives the list of titrants. Group IGroup IIP. Alkalinity1. N/35.5 AgNO3Q. Hardness2. N/40 Na2 S2O3R. Chloride3. N/50 H2SO4S. Dissolved oxygen4. N/50 EDTAThe correct match of water quality parameters in Group I with titrants in Group II is |
| A. | P-1, Q-2, R-3, S-4 |
| B. | P-3, Q-4, R-1, S-2 |
| C. | P-2, Q-1, R-4, S-3 |
| D. | P-4, Q-3, R-2, S-1 |
| Answer» D. P-4, Q-3, R-2, S-1 | |
| 16. |
The Ca2+ concentration and Mg2+ concentration of a water sample are 160 mg/L and 40 mg/L as their ions respectively. The total hardness of this water sample in terms of CaCO3 in mg/L is approximately equal to |
| A. | 120 |
| B. | 200 |
| C. | 267 |
| D. | 567 |
| Answer» E. | |
| 17. |
The non-carbonate hardness of the sample in mg/l as CaCO3 is |
| A. | 225 |
| B. | 156 |
| C. | 86 |
| D. | 0 |
| Answer» C. 86 | |
| 18. |
The total hardness of the sample in mg/l as CaCO3 is |
| A. | 484 |
| B. | 450 |
| C. | 242 |
| D. | 225 |
| Answer» E. | |
| 19. |
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 6m /s |
| A. | 20.58 m |
| B. | 21.58 m |
| C. | 23.58 m |
| D. | 22.58 m |
| Answer» E. | |
| 20. |
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 2 cm /s. The minimum surface area (in m ) required for this settling tank to remove particles of size 0.06 mm and above with 100% efficiency is _________ |
| A. | 31.09 m |
| B. | 32 m |
| C. | 31.21 m |
| D. | 30 m |
| Answer» D. 30 m | |
| 21. |
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 4 104 producing optimal results. The alum quantity required for 30 days (in kg) of operation of the plant is __________ |
| A. | 37800 kg |
| B. | 35600 kg |
| C. | 32800 kg |
| D. | 3240 kg |
| Answer» B. 35600 kg | |
| 22. |
The amount of CO2 generated (in kg) while completely oxidizing one kg of CH4 to the end products is _________. |
| A. | 3.25 kg CO |
| B. | 2.75 kg CO |
| C. | 1.75 kg CO |
| D. | 2.50 kg CO |
| Answer» C. 1.75 kg CO | |
| 23. |
The following chemical is used for coagulation |
| A. | Ammonium Chloride |
| B. | Aluminium Chloride |
| C. | Aluminium Sulphate |
| D. | Copper Sulphate |
| Answer» E. | |
| 24. |
A town has an existing horizontal flow sedimentation tank with an overflow rate of 17m /day/m , and it is desirable to remove particles that have settling velocity of 0.1 mm/s. Assuming the tank is an ideal sedimentation tank, the percentage of particles removal is approximately equal to |
| A. | 30% |
| B. | 50% |
| C. | 70% |
| D. | 90% |
| Answer» C. 70% | |
| 25. |
The unit in which both sedimentation and digestion processes of sludge take place simultaneously is |
| A. | Skimming Tank |
| B. | Imhoff Tank |
| C. | Detritus Tank |
| D. | Digestion Tank |
| Answer» D. Digestion Tank | |
| 26. |
Chlorine gas used for disinfection combines with water to form hypochlorous acid (HOCl). The HOCl ionizes to form hypochlorite (OCl |
| A. | 4.3 |
| B. | 6.6 |
| C. | 7.5 |
| D. | 9.4 |
| Answer» E. | |
| 27. |
A water treatment plant is required to process 28800 m /d of raw water (density = 1000 kg/m , kinematic viscosity = 10 6 m /s). The rapid mixing tank imparts a velocity gradient of 900s |
| A. | 32.4 |
| B. | 36 |
| C. | 324 |
| D. | 32400 |
| Answer» E. | |
| 28. |
A settling tank in a water treatment plant is designed for a surface overflow rate of 30(m /day.m ) . Assume specific gravity of sediment particles = 2.65, density of water ( ) = 1000 kg/m , dynamic viscosity of water (m) = 0.001 N.s/m , and Stokes law is valid. The approximate minimum size of particles that would be completely removed is |
| A. | 0.01 mm |
| B. | 0.02 mm |
| C. | 0.03 mm |
| D. | 0.04 mm |
| Answer» C. 0.03 mm | |
| 29. |
The results of analysis of a raw water sample are given below |
| A. | Turbidity followed by disinfection |
| B. | Fluorides and Hardness |
| C. | Iron, followed by disinfection |
| D. | Both (b) and (c) |
| Answer» D. Both (b) and (c) | |
| 30. |
The potable water is prepared from turbid surface water by adopting the following treatment sequence. |
| A. | Turbid surface water Coagulation Flocculation Sedimentation Filtration Disinfection Storage & Supply |
| B. | Turbid surface water Disinfection Flocculation Sedimentation Filtration Coagulation Storage & Supply |
| C. | Turbid surface water Filtration Sedimentation Disinfection Flocculation Coagulation Storage & Supply |
| D. | Turbid surface water Sedimentation Flocculation Coagulation Disinfection Filtration Storage & Supply |
| Answer» E. | |
| 31. |
Some of the water quality parameters are measured by titrating a water sample with a titrant. Group I gives a list of parameters and Group II gives the list of titrants. |
| A. | P-1, Q-2, R-3, S-4 |
| B. | P-3, Q-4, R-1, S-2 |
| C. | P-2, Q-1, R-4, S-3 |
| D. | P-4, Q-3, R-2, S-1 |
| Answer» D. P-4, Q-3, R-2, S-1 | |
| 32. |
The theoretical oxygen dmenad of a 0.001 mol/L glucose solution is |
| A. | 180 mg/L |
| B. | 192 mg/L |
| C. | 90 mg/L |
| D. | 96 mg/L |
| Answer» C. 90 mg/L | |
| 33. |
For a water treatment plant having a flow rate of 432m /hr, what is the required plan area of a Type I setting tank to remove 90% of the particles having a settling velocity of 0.12 cm/sec is |
| A. | 120 m |
| B. | 111 m |
| C. | 90 m |
| D. | 100 m |
| Answer» D. 100 m | |
| 34. |
The Ca |
| A. | 120 |
| B. | 200 |
| C. | 267 |
| D. | 567 |
| Answer» E. | |
| 35. |
Total Kjeldahl Nitrogen (TKN) concentration (mg/L as N) in domestic sewage is the sum of the concentrations of: |
| A. | Organic and inorganic nitrogen in sewage |
| B. | Organic nitrogen and nitrate in sewage |
| C. | Organic nitrogen and ammonia in sewage |
| D. | Ammonia and nitrate in sewage Problem Based MCQs |
| Answer» D. Ammonia and nitrate in sewage Problem Based MCQs | |
| 36. |
The present population of a community is 28000 with an average water consumption of 4200m /d. The existing water treatment plant has a design capacity of 6000 m /d. It is expected that the population will increase to 44000 during the next 20 years. The number of years from now when the plant will react its design capacity, assuming an arithmetic rate of population growth, will be |
| A. | 5.5 years |
| B. | 8.6 years |
| C. | 15.0 years |
| D. | 16.5 years |
| Answer» D. 16.5 years | |
| 37. |
An ideal horizontal flow setting basin in 3m deep having surface area 900 m . Water flows at the rate of 8000 m /d, at water temperature 20 C (m = 10 kg/m.s and p = 1000 kg/m ). Assuming Stokes law to be valid, the proportion (percentage) of spherical sand particles (0.01 mm in diameter with specific gravity 2.65), that will be removed is |
| A. | 32.5 |
| B. | 67 |
| C. | 87.5 |
| D. | 95.5 |
| Answer» D. 95.5 | |
| 38. |
Group 1 contains some properties of water/wastewater and group 2 contains list of some tests on water/waste water Match the property with corresponding test. |
| A. | P 2, Q 1, R 4, S 3 |
| B. | P 4, Q 1, R 2, S 3 |
| C. | P 2, Q 4, R 1, S 3 |
| D. | P 4, Q 2, R 1, S 3 |
| Answer» C. P 2, Q 4, R 1, S 3 | |
| 39. |
Hardness of water is directly measured by titrated with ethylene-di-amine-tetracetic acid (EDTA) using |
| A. | feriochrome black T indicator |
| B. | ferroin indicator |
| C. | methyl orange indicator |
| D. | phenolphthalein indicator |
| Answer» E. | |
| 40. |
1 TCU is equivalent to the colour produced by |
| A. | 1 mg/L of chlorplatinate ion |
| B. | 1 mg/L of platinum ion |
| C. | 1 mg/L Platinum in form of chlorplatinate ion |
| D. | 1 mg/L of organo-chlorplatinate ion |
| Answer» D. 1 mg/L of organo-chlorplatinate ion | |
| 41. |
Total Kjedahl nitrogen is a measure of |
| A. | total organic nitrogen |
| B. | total organic and ammonia nitrogen |
| C. | total ammonia nitrogen |
| D. | total inorganic and ammonia nitrogen |
| Answer» C. total ammonia nitrogen | |
| 42. |
The organism, which exhibits very nearly the characteristics of an ideal pathogenic indicator is |
| A. | Entamoeba histolytica |
| B. | Escherichia coli |
| C. | Salmonella typhi |
| D. | Vibrio comma |
| Answer» B. Escherichia coli | |
| 43. |
The presence of hardness in excess of permissible limit causes |
| A. | cardio vascular problems |
| B. | skin discolouration |
| C. | calcium deficiency |
| D. | increased laundry expenses |
| Answer» E. | |
| 44. |
The alkalinity and hardness of a water sample are 250 mg/l and 350 mg/l as CaCO |
| A. | 350 mg/l carbonate hardness and zero non-carbonate hardness. |
| B. | 250 mg/l carbonate hardness and zero non-carbonate hardness. |
| C. | 250 mg/l carbonate hardness and 350 mg/l noncarbonate hardness. |
| D. | 250 mg/l carbonate hardness and 100 mg/l noncarbonate hardness. |
| Answer» E. | |
| 45. |
A synthetic sample of water is prepared by adding 100 mg Kaolinite (a clay mineral), 200 mg glucose, 168 mg NaCl, 120 mg MgSO |
| A. | 699 and 599 |
| B. | 599 and 399 |
| C. | 699 and 199 |
| D. | 699 and 399 |
| Answer» B. 599 and 399 | |
| 46. |
A town is required to treat 4.2 m /min of raw water for daily domestic supply. Flocculating particles are to be produced by chemical coagulation. A column analysis indicated that an overflow rate of 0.2 mm/s will produce satisfactory particle removal in a settling basin at a depth of 3.5 m. The required surface area (in m ) for settling is |
| A. | 210 |
| B. | 350 |
| C. | 1728 |
| D. | 21000 |
| Answer» C. 1728 | |
| 47. |
Total hardness in mg/l as CaCO |
| A. | 1500 |
| B. | 2000 |
| C. | 3000 |
| D. | 5000 |
| Answer» C. 3000 | |
| 48. |
Anaerobically treated effluent has MPN of total coliform as 10 |
| A. | %R = 99.90; log R = 4 |
| B. | %R = 99.90; log R = 2 |
| C. | %R = 99.99; log R = 4 |
| D. | %R = 99.99; log R = 2 |
| Answer» D. %R = 99.99; log R = 2 | |
| 49. |
The number of filters required shall be |
| A. | 3 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» D. 8 | |
| 50. |
The surface area required for the rapid sand after will be |
| A. | 210 m |
| B. | 215 m |
| C. | 216 m |
| D. | 218 m |
| Answer» D. 218 m | |