Waste Water Engineering Multiple Choice Questions on “Principles of House Drainage”.
1. The sewers should be laid ______
a) Below the building
b) Side of the building
c) Within the building
d) Across the building
Answer: b
Clarification: It is advisable to lay sewers by the side of the building rather than below the building. The drains should be laid at an angle of 180˚ between the inspection manholes.
2. What is the angle between the drains and inspection manholes?
a) 45˚
b) 90˚
c) 135˚
d) 180˚
Answer: d
Clarification: The drains should be laid at an angle of 180˚ between the inspection manholes. Drains from different houses should be connected to public sewers only if the level permits.
3. The entire system should be ventilation free.
a) True
b) False
Answer: b
Clarification: The entire sewer system should have proper ventilation. The house drainage should be containing enough number of traps at suitable points for the efficient functioning of it. The joints should be watertight.
4. _________ is the removal of excess surface water from the land to enhance crop growth.
a) Sewer drainage
b) Agricultural drainage
c) Municipal drainage
d) Soil drainage
Answer: b
Clarification: Agricultural land drainage is the removal of excess surface and subsurface water from the land to enhance crop growth, including the removal of soluble salts from the soil.
5. Which of the following is not correct with respect to installing the drainage system in the waterlogged land?
a) Increase in water amount in soil
b) Reduction in water amount on soil
c) Discharge of water through the system
d) Reducing waterlogging
Answer: a
Clarification: The direct effects of installing a drainage system in the waterlogged land are the reduction in the average amount of water in the soil mass and on the surface soil inducing drier soil conditions.
6. Which of these is negative effect owing to the drier soil conditions?
a) Aeration of soil
b) Soil structure
c) Availability of nitrogen
d) Irrigation efficiency
Answer: d
Clarification: Aeration of the soil increases with improved soil structure and availability of the nitrogen. Irrigation efficiency is negative.
7. Which of these is a positive effect owing to the drier soil conditions?
a) Irrigation efficiency
b) Risk of drought
c) Organic matter
d) Crop production
Answer: d
Clarification: The positive effects are increased aeration of the soil, stabilized soil structure, higher availability of nitrogen in the soil, higher and more diversified crop production and better workability of the land.
8. Which of these is a positive effect owing to the discharge?
a) Leaching of nutrients
b) Environmental damage
c) Interference with infrastructural elements of land
d) Removal of salts
Answer: d
Clarification: Positive effects owing to the discharge are the removal of salts or other harmful substances from the soil, availability of drainage water for various purposes.
9. What is the time required for the depletion of oxygen in soil by waterlogging?
a) 6-12 hours
b) 1-2 days
c) 3-6 days
d) 1-4 weeks
Answer: b
Clarification: The adverse effects of drainage may be broadly classified as impaired crop growth, formation of water logged soils waterlogging- causes oxygen deficits in soils, usually within 1-2 days.
10. What is the average land coverage of vertisols in Ethiopia?
a) 5 million ha
b) 10 million ha
c) 13 million ha
d) 16 million ha
Answer: c
Clarification: Vertisols (deep black clay soils) cover about 13 million ha in Ethiopia. The highland Vertisols above 1500 m altitude cover 7.6 million ha, of which 1.93 million ha are currently cropped (about 23% of all Ethiopian crop land).
11. What is the power of diminishment of van der Waals force with respect to distance?
a) 2
b) 4
c) 6
d) 8
Answer: c
Clarification: Water molecules are attracted to solid surfaces by various types of London-van der Waals forces. These are strong, but very short-range forces; they diminish with about the sixth power of the distance.