Engineering Questions with Answers - Multiple Choice Questions
Environmental Engineering MCQ’s – Desalination
1 - Question
Which of the following method is not used for desalination?
a) Distillation
b) Coagulation
c) Reverse osmosis
d) Freezing
View Answer
Answer: a
Explanation: Coagulation is not used for desalination. It is done for removing the suspended impurities from water.
2 - Question
Which of the following is not a type of distillation plant?
a) Vertical tube evaporator
b) Multistage flash evaporator
c) Tube settler
d) Multi-effect multistage flash evaporator
View Answer
Answer: c
Explanation: Tube settler is not a type of distillation plant. It is used for shallow depth sedimentation.
3 - Question
Multistage flash evaporator produces _____ kg of water per kg of prime steam.
a) 5
b) 10
c) 15
d) 20
View Answer
Answer: d
Explanation: Multistage flash evaporator produces 20 kg of water per kg of prime steam.
They operate on the brine recycling basis.
Explanation: Multistage flash evaporator produces 20 kg of water per kg of prime steam.
They operate on the brine recycling basis.
4 - Question
Which of the following is the best evaporative desalinating method?
a) Vertical tube evaporator
b) Multistage flash evaporator
c) Tube settler
d) Multi-effect multistage flash evaporator
View Answer
Answer: b
Explanation: Multistage flash evaporator is the best evaporative desalinating method in which the efficiency of multistage flash evaporator can be further improved by the use of flash enhancers.
5 - Question
The number of stages involved in the desalination using a multistage flash evaporator is _________________
a) 20
b) 38
c) 49
d) 69
View Answer
Answer: d
Explanation: Multistage flash evaporator uses 69 stages in the desalination process. The vapors released during flash each stage condenses to heat the incoming sea water and gives fresh water.
Explanation: Multistage flash evaporator uses 69 stages in the desalination process. The vapors released during flash each stage condenses to heat the incoming sea water and gives fresh water.
6 - Question
Which of the following desalination method is more suitable for brackish water than sea water?
a) Distillation
b) Solar evaporation
c) Reverse osmosis
d) Freezing
View Answer
Answer: c
Explanation: Reverse osmosis is more suitable for brackish water than sea water. In this process, some part of water permeates the membrane and is collected as fresh water while the remaining water passed through the turbine for recovery.
7 - Question
The process in which the brackish water is forced across a permeable membrane by mechanical forces is called as _____________
a) Filtration
b) Semi filtration
c) Coagulation
d) Hyper filtration
View Answer
Answer: d
Explanation: The process in which the brackish water is forced across a permeable membrane by mechanical forces is called as hyper filtration. The pressure applied must be greater than the osmotic pressure.
8 - Question
In which desalination process, the salt ions are removed from seawater by means of electric current?
a) Distillation
b) Electro-dialysis
c) Reverse osmosis
d) Freezing
View Answer
Answer: b
Explanation: In Electro dialysis, the salt ions are removed from seawater by means of electric current where two membranes are used- one who is more selective to anode and another who is more selective to cathode.
9 - Question
In Electro-dialysis, the electric energy which required is _____________
a) Directly proportional to cation permeable membrane
b) Directly proportional to anion permeable membrane
c) Directly proportional to salt concentration
d) Inversely proportional to salt concentration
View Answer
Answer: c
Explanation: In Electro-dialysis, the passage of electric current helps the diffusion of cation and anion permeable membrane and the energy required is directly proportional to the concentration of salt in the saline water.
10 - Question
The maximum salt concentration up to which desalination of brackish water is possible by Electro-dialysis is _____________
a) 1000ppm
b) 2000ppm
c) 3000ppm
d) 5000ppm
View Answer
Answer: d
Explanation: Electro-dialysis is suitable for brackish water with a total concentration of salt up to 5000ppm and leaving 100ppm in the treated water.
11 - Question
In which desalination process, the cooling of sea water is done to obtain fresh water?
a) Distillation
b) Electro-dialysis
c) Reverse osmosis
d) Freezing
View Answer
Answer: d
Explanation: In freezing method of desalination, cooling of the water takes place to obtain fresh water by separation of the ice and brine liquor.
12 - Question
The pressure freezing process works on the vacuum free vapor compression principle.
a) True
b) False
View Answer
Answer: b
Explanation: Zarchin colt freezing process works on the vacuum free vapor compression principle. In this process, water is used as a refrigerant.
13 - Question
In which desalination process, solar energy is used?
a) Reverse osmosis
b) Freezing
c) Electro-dialysis
d) Solar evaporation
View Answer
Answer: d
Explanation: In the solar evaporation, the solar energy is used as a source of heat energy. The solar energy striking the earth is estimated to be a 250BTU / day/m2.
14 - Question
The solar evaporation can yield about ___ kg of fresh water per day per m2 of basin surface.
a) 5
b) 10
c) 15
d) 20
View Answer
Answer: a
Explanation: The solar evaporation can yield about 5 kg of fresh water per day per m2 of basin surface under good sunshine conditions. The solar energy is absorbed by salt water and fresh water is produced.