RRB JE Stage II : Civil Engineering Quiz | 21st August

Dear aspirants,

RRB JE Stage II exam is scheduled to be conducted from 28th August to 1st September2019. The overall merit for the selection will be made on the basis of the marks scored in stage II, so candidates need to prepare thoroughly for the second stage. To help the aspirants, Adda247 has come up with a study plan in which we will provide you daily quizzes of all technical subjects. The below quiz will be helpful for the candidates who opted Civil as the exam group in RRB JE stage II.

Q1. Biochemical oxygen demand (BOD) is quoted at which temperature?
(a) 25°C
(b) 20°C
(c) 15°C
(d) 10°C

S1. Ans.(b)
Sol.

Q2. Coagulation-flocculation with alum is performed
(a) immediately before chlorination
(b) immediately after chlorination
(c) after rapid sand filtration
(d) before rapid sand filtration

S2. Ans.(d)
Sol. The use of coagulant is generally necessary for clarifying raw waters containing turbidities greater than 30 to 50 mg/l, but in actual practice, plain sedimentation is rarely used these days, and the coagulation before sedimentation is almost universally adopted in all the major water treatment plants, and is followed by rapid sand filtration.

Q3. Total Kjeldahl 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

S3. Ans.(b)
Sol. The sum total of organic nitrogen and ammonia nitrogen is called Kjeldahl nitrogen.

Q4. The treatments which are generally given to treat raw water supplies, follow the sequence
(a) screening, sedimentation, disinfection, filtration
(b) screening, sedimentation, filtration, disinfection
(c) screening, sedimentation, disinfection, aeration
(d) screening sedimentation, coagulation filtration, disinfection

S4. Ans.(b)
Sol. Most of the big and visible objects, such as trees, branches, sticks, vegetations, fish, animal life, etc., present in raw waters of surface sources can be removed by screening. The coarser suspended materials can than be removed by letting the water settle in sedimentation basins. This process is called plain sedimentation. The finer particles in suspension, which may avoid settling in sedimentation basins even after using chemical coagulation, may then be removed by filtering the water through filters. This process is called filtration. The filtered water which may still contain pathogenic bacteria, is then made bacteria-proof by adding certain chemicals such as chlorine, ozone etc. This process is called disinfection.

Q5. In the design of a sedimentation tank the essential factor to be considered is
(a) depth of tank
(b) turbidity of water
(c) concentration of suspended solids in the water
(d) surface loading of tank

S5. Ans.(d)
Sol. Surface loading of tank should be less than the settling velocity of discrete particles for effective sedimentation.

Q6. The rapid gravity filters, as compared to slow sand filters, have
(a) much smaller area
(b) more flexibility
(c) faster action
(d) all the above

S6. Ans.(d)
Sol.

Q7. Manholes are generally located
(a) at all changes of direction of sewer
(b) at all changes of gradient of sewer
(c) at all junctions of different sewers
(d) All of the above

S7. Ans.(d)
Sol.

Q8. BOD_5 represents 5 days-biochemical oxygen demand at a temperature of
(a) 0°C
(b) 20°C
(c) 30°C
(d) None of these

S8. Ans.(b)
Sol.

Q9. The ultimate BOD value of a waste
(a) increases with temperature
(b) decreases with temperature
(c) remains the same at all temperatures
(d) doubles with every 10°C rise in temperature

S9. Ans.(c)
Sol. Ultimate BOD represents the biode-gradable organic matter, so it will remain unchanged.

Q10. During preliminary treatment of sewage
(a) oils and greases are removed by skimming tanks
(b) floating materials are removed by screening
(c) grit and sand are removed by grit chambers
(d) All of the above are correct

S10. Ans.(d)
Sol.

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