Environmental Engineering 18

Objective Questions and Answers of Civil Engineering: Environmental Engineering 18

Subject: Environmental Engineering 18

Part 18: Objective questions and answers of Environmental Engineering


Q1. The design discharge for the combined sewer system shall be taken as

a) Equal to rainfall

b) Rainfall + dwf

c) Rainfall + 2 dwf

d) Rainfall + 6 dwf


Q2. The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is

a) Separate system

b) Combined system

c) Partially separate system

d) Partially combined system


Q3. The specific gravity of sewage is

a) Much greater than 1

b) Slightly less than 1

c) Equal to 1

d) Slightly greater than 1


Q4. 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

a) Check valve

b) Sluice valve

c) Safety valve

d) Scour valve


Q5. For a country like India, where rainfall is mainly confined to one season, the suitable sewerage system will be

a) Separate system

b) Combined system

c) Partially combined system

d) Partially separate system


Q6. A sewer that receives the discharge of a number of house sewers is called

a) House sewer

b) Lateral sewer

c) Intercepting sewer

d) Submain sewer


Q7. Sewerage system is usually designed for

a) 10 years

b) 25 years

c) 50 years

d) 75 years


Q8. If the time of concentration is 9 minutes, then the intensity of rainfall according to british ministry of health formula will be

a) 4 mm/hr

b) Lomm/hr

c) 20 mm/hr

d) 40 mm/hr


Q9. The slope of sewer shall be

a) Given in the direction of natural slope of ground

b) Given in the direction opposite to natural slope of ground

c) Zero

d) Steeper than 1 in 20


Q10. The main disadvantage of cement concrete sewers is

a) Less strength

b) Difficulty in construction

c) Difficulty in transportation due to heavy weight

d) Less life


Q11. Which of the following retards the self-purification of stream?

a) Higher temperature

b) Sunlight

c) Satisfying oxygen demand

d) None of the above


Q12. Select the correct statement.

a) 5 day bod is the ultimate bod.

b) 5 day bod is greater than 4 day bod keeping other conditions same.

c) 5 day bod is less than 4 day bod keeping other conditions same.

d) Bod does nof depend on time.


Q13. The effect of increasing diameter of sewer on the self-cleansing velocity is

a) To decrease it

b) To increase it

c) Fluctuating

d) Nil


Q14. The most commonly used sewer under culverts is

a) Circular brick sewer

b) Circular cast iron sewer

c) Semi-elliptical sewer

d) Horse-shoe type sewer


Q15. An egg shaped section of sewer

a) Is economical than circular section

b) Provides self-cleansing velocity at low discharges

c) Is more stable than circular section

d) Is easy to construct


Q16. The rate of bod exerted at any time is

a) Directly proportional to bod satisfied

b) Directly proportional to bod remain-ing ,

c) Inversely proportional to bod satisfied

d) Inversely proportional to bod re-maining


Q17. The characteristics of fresh and septic sewage respectively are

a) Acidic and alkaline

b) Alkaline and acidic

c) Both acidic

d) Both alkaline


Q18. Standard bod is measured at

a) 20°c – 1day

b) 25°c- 3day

c) 20°c – 5day

d) 30°c- 5day


Q19. 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 20°c. The bod of raw sewage will be

a) 100 ppm

b) 200 ppm

c) 300 ppm

d) 400 ppm


Q20. The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy bod, is

a) 1

b) 100

c) Infinite

d) Zero


Part 18: Objective questions and answers of Environmental Engineering


Q1. Answer c


Q2. Answer b


Q3. Answer d


Q4. Answer b


Q5. Answer a


Q6. Answer b


Q7. Answer b


Q8. Answer d


Q9. Answer a


Q10. Answer c


Q11. Answer d


Q12. Answer c


Q13. Answer b


Q14. Answer a


Q15. Answer b


Q16. Answer b


Q17. Answer b


Q18. Answer c


Q19. Answer b


Q20. Answer b