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Environmental Engineering Quiz | Environmental Engineering Objective Type Questions and Answers

(21) The effective size of sand particles used in slow sand filters is
[A] 0.25 to 0.35 mm
[B] 0.35 to 0.60 mm
[C] 0.60 to 1.00 mm
[D] 1.00 to 1.80 mm
Answer: 0.25 to 0.35 mm
(22) As compared to rapid sand filters, slow sand filters give

i) slower filtration rate

ii) higher filtration rate

iii) lesser efficiency in removal of bacteria

iv) higher efficiency in removal of bacteria The correct answer is

[A] (i) and (ii)
[B] (ii) and (iii)
[C] (i) and (iv)
[D] (ii) and (iv)
Answer: (i) and (iv)
(23) Period of cleaning of slow sand filters is about
[A] 24 - 48 hours
[B] 10-12 days
[C] 2-3 months
[D] 1-2 year
Answer: 2-3 months
(24) Double filtration is used
[A] To Increase The Filtration Slow Sand Filters Capacity Of
[B] To Increase The Filtration Rapid Sand Filters Capacity Of
[C] For Isolated Buildings Like Pools, Hotels Etc Swimming
[D] All Of The Above
Answer: To Increase The Filtration Slow Sand Filters Capacity Of
(25) Disinfection of water results in
[A] Removal Of Turbidity
[B] Removal Of Hardness
[C] Killing Of Disease Bacteria
[D] Complete Sterilisation
Answer: Killing Of Disease Bacteria
(26) Chlorine demand of water is equal to
[A] Applied Chlorine
[B] Residual Chlorine
[C] Sum Of Applied And Residual Chlorine
[D] Difference Of Applied And Residual Chlorine
Answer: Difference Of Applied And Residual Chlorine
(27) The percentage of chlorine in fresh bleaching powder is about
[A] 10 to 15
[B] 20 to 25
[C] 30 to 35
[D] 40 to 50
Answer: 30 to 35
(28) Which of the following chemical compounds can be used for dechlorination of water ?
[A] Carbon Dioxide
[B] Bleaching Powder
[C] Sulphur Dioxide
[D] Chloramines
Answer: Sulphur Dioxide
(29) As compared to higher pH values, the contact period required for efficient chlorination at lower pH values is
[A] Smaller
[B] Larger
[C] Same
[D] None Of The Above
Answer: Smaller
(30) Disinfection efficiency is
[A] Reduced At Higher Ph Value Of Water
[B] Unaffected By Ph Value Of Water
[C] Increased At Higher Ph Value Of Water
[D] Highest At Ph Value Equal To 7
Answer: Reduced At Higher Ph Value Of Water
31 Which of the following compounds is widely used for algae control ?
[A] Sodium Sulphate
[B] Copper Sulphate
[C] Sodium Chloride
[D] Calcium Chloride
Answer: Copper Sulphate
32 The suitable layout of a distribution system for irregularly growing town is
[A] Dead End System
[B] Grid Iron System
[C] Radial System
[D] Ring System
Answer: Dead End System
33 The suitable layout of distribution system for a city with roads of rectangular pattern is
[A] Grid Iron System
[B] Dead End System
[C] Ring System
[D] Radial System
Answer: Grid Iron System
34 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
Answer: Sluice Valve
35 Scour valves are provided
[A] At Street Corners To Control The Flow Of Water
[B] At Every Depression And Dead Ends To Drain Out The Waste Water That May Collect There
[C] At The Foot Of Rising Main Along The Slope To Prevent Back Running Of Water
[D] At Every Summit Of Rising Mains
Answer: At Every Depression And Dead Ends To Drain Out The Waste Water That May Collect There
36 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
Answer: Lateral Sewer
37 Average rate of water consumption perhead per day as per Indian Standard is
[A] 100 litres
[B] 135 litres
[C] 165 litres
[D] 200 litres
Answer: 135 litres
38 Sewerage system is usually designed for
[A] 10 years
[B] 25 years
[C] 50 years
[D] 75 years
Answer: 25 years
39 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
Answer: 40 mm/hr
40 The self cleansing velocity for all sewers in India is usually
[A] less than 1.0 m/sec
[B] 1.0 m/sec to 1.2 m/sec
[C] 1.5 m/sec to 2.0 m/sec
[D] 3.0 m/sec to 3.5 m/sec
Answer: 1.0 m/sec to 1.2 m/sec

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