QUIZ : CIVIL ENGINEERING(22 DEC 2020)

Quiz: Civil Engineering
Exam: SSC-JE
Topic: ENVIRONMENT ENGINEERING

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. The commonly used indicator for measuring iron concentration in water is
(a) Eriochrome black T
(b) 1, 10, phenanthroline
(c) Phenolphthalein
(d) Blue litmus
Q2. Which of the following cations impart(s) pseudo-hardness to water?
(a) Calcium only
(b) Magnesium only
(c) Calcium and magnesium
(d) sodium
Q3. Cleaning of slow sand filters is done by
(a) Scrapping the top layer and removal of sand
(b) back washing
(c) any of the above
(d) None of these
Q4. Air-binding phenomenon in rapid sand filters may occur due to
(a) excessive negative pressure
(b) mud ball formation
(c) higher turbidity in the effluent
(d) low temperature
Q5. In a rapid gravity filter working with regard to water, quality gets affected due to
(a) cracking of filters
(b) mud balls formation
(c) air binding
(d) All of above
Q6. At break point chlorination the residual chlorine is
(a) zero
(b) minimum
(c) maximum
(d) reappears
Q7. The suitable layout for a water supply distribution system, for a city of roads of rectangular pattern, is
(a) dead end system
(b) grid iron system
(c) ring system
(d) radial system
Q8. The drop manholes are provided in a sewerage system when there is
(a) change in alignment of sewer line
(b) change in size of sewers
(c) change in the elevation of ground level
(d) change from gravity system to pressure system
Q9. Imhoff cone is used to measure, in sewage:
(a) total solids
(b) total organic solids
(c) total inorganic solids
(d) settleable solids
Q10. Standard 5 day BOD at 20°C, when compared to ultimate BOD, is about
(a) 58%
(b) 68%
(c) 98%
(d) None of these

SOLUTION

S1. Ans.(b)
Sol. Erichrome black-T is used to measure hardness. Phenolphthalein is used to measure alkalinity blue litmus is used to measure acidity of water.

S2. Ans.(d)
Sol. Monovalent Cations import pseudo hardness. Hardness is the concentration of multivalent cations.

S3. Ans.(a)
Sol. The cleaning of slow sand filter is done by scrapping the concentration of multivalent cations.
S4. Ans.(a)
Sol. Negative pressure tends to release the air dissolved in water. It causes the formation of bubbles which stick to the sand grains and affects the working of the filter.
S5. Ans.(d)
Sol. Cracking of filters, mud ball formation and air binding are operational problems of rapid gravity filter which is affect its cleaning efficiency

S6. Ans.(d)
Sol. Any chlorine that is added to water beyond break point breaks through the water and appears as residual chlorine.

S7. Ans.(b)
Sol. Grid iron system is suitable layout for a water supply distribution system for a city of roads of rectangular pattern.
S8. Ans.(c)
Sol. When a branch sewer enters a manhole by more than 0.5 to 0.6m above the main sewer the sewage is generally not allowed to fall directly in to the manhole but is brought into it through a down pipe taken from the branch sewer to the bottom of the manhole. the manhole in which a vertical pipe is used is called drip manhole
S9. Ans.(d)
Sol. The quantity of settlable solids can be determined easily with the help of a specially designed conical glass vessel called Imhoff cone.

S10. Ans.(b)
Sol. The BOD of water during 5 day at 20°C is 68% of total demand A 10day BOD is about 90% of total.

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