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MCQ
61. Slow sand filter is efficient to remove the bacteria from the raw water to an extent of-
50%
70%
85%
99%
ব্যাখ্যা: The slow sand filters are highly efficient in the removal of bacteria and can remove around 98%-99% of bacteria present in water.
62. Absolute zero temperature = ?
0°C
273°C
-273°C
None
ব্যাখ্যা: The coldest possible temperature is called absolute zero temperature. This temperature is 0°K or-273°C
63. A pipe conveying sewage from plumbing system of a single building to common sewer is called-
house sewer
lateral sewer
main sewer
submain sewer
ব্যাখ্যা: Main sewer as the primary pipeline in a sewerage system to which all the branching pipes carrying sewage from different location. Submain sewer means a city or privated owned sewer pipe designed to convey sewage from two or more building laterals to a main sewer.
64. A manhole is generally provided at each-
bend
change of gradient
junction
all the above
ব্যাখ্যা: A manhole is an opening to a confined space such as a shaft, utility valult. Manhole is generally provided at each bend, Junction, change of gradient, change of sewer diameter.
65. The term sullage refers to-
fresh waste water
waste water from kitchen and laundry
septic waste water
toxic waste water
ব্যাখ্যা:Sullage is all the wastewater generated in households or office buildings from streams without fecal contamination.
66. Standard BOD is measured at-
20°C-1 day
25°C-3 day
20°C-5 day
30°C-5 day
ব্যাখ্যা: BOD-এর সাহায্যে পানিতে অক্সিজেনের মাত্রা কতটুকু আছে Oxyzen Demand। পানির বিশুদ্ধতা পরিমাপ করার জন্য ৫ তা পরিমাপ করা হয়। BOD-এর পূর্ণরূপ Biochemical দিন 20℃ তাপমাত্রা প্রয়োগ করা হয়।
67. Disinfection of water results in-
Removal of turbidity
Removal of taste
Killing of disease bacteria
Removal of hardness
ব্যাখ্যা: Water disinfection means the removal, deactivation or killing of pathogenic microorganisms.
68. Main element of biogas is
CO2
Cow dung
Water
CH4
ব্যাখ্যা: Typical composition of biogas- Methane 50-80% Carbon dioxide 25-50% Nitrogen 0-10% Hydrogen 0-1% Hydrogen sulphide 0-3% So the main element of biogas is Methane
69. The maximum permissible limit for iron in drinking water is-
0.1 mg/L
0.3-1 mg/L
2-2.5 mg/L
5 mg/L
70. What do you mean by BOD?
Best organized demand
Biochemical oxygen demand
Before oxidation damage
Bacteria of damage
ব্যাখ্যা: The full name of BOD is Biochemical Oxygen Demand. BOD refers to the amount of dissolved oxygen (DO) that arrobic organism need in order to break down organic naterial in water over time.
71. The most common coagulant is-
magnesium culfater
alum
chlorine
bleaching powder
72. What is the example of metamorphic rock?
granite
genesis
marble
all of these
ব্যাখ্যা: A marble is an example of a metamorphic rock It is composed of recrystallized carbonated minerals, most commonly calcite or dolomite.
73. Which of the following protects penstock due to sudden variation of flow or velocity of water?
Anchors
Trash rack
Forebays
Surge tank
ব্যাখ্যা: Surge tank connected to a pipe carrying a liquid and intended to neutralized sudden change of pressure in the flow by filing when the pressure increases and emptying when it drops.
74. Arsenic contamination has primarily affected-
the deep aquifer
the river
the shallow aquifer
none
ব্যাখ্যা: Arsenic contamination has primarity affected the shallow aquifer and Arsenic free from deep aquifer.
75. The diameter of a domestic sewer pipe laid at gradient 1 in 100 is recommended ------
100 mm
200mm
150mm
175mm
ব্যাখ্যা: All sanitary sewage of domestic and other water borne wastes shall be collected and conveyed in a sanitary sewer pipe. These recommended gradients are 1 in 30 (75mun pipe), 1 in 40 (100 mm pipe) and 1 in 100 (150 mm pipe).
76. The maximum permissible quantity of lead in water for domestic supplies is-
0.01 ppm
0.05 ppm
0.50 ppm
1 ppm
77. The presence of sodium chloride in water-
stops epidemic
increases hardness of water
causes bad taste
softens the water
78. The water obtained from a lake is known as surface water.
Agree
Disagree
79. The water obtained from is generally known as sub-surface water---
rain
reservoirs
rivers
artesian wells
80. Absolute pure water is good for health.
right
wrong