The efficiency of chlorine increase by

When the pH of the water increases

When the pH of the water decreases

The expression loge N1/N = – kt m Where, m is a constant such that m>1 represents

Rate of the kill will decrease with time

Rate of the kill will remains constant with time

Rate of the kill will increase with time

Rate of the kill will decrease with time

Rate of the kill is directly proportional to time

When the coefficient of dilution is 1, then which of the following statement is correct?

Efficiency of dilution decreases.

Time of contact is more important than dosage

The dosage is more important than time of contact

Concentration and time are equally important

Efficiency of dilution decreases.

Which method of disinfection is mainly used in rural areas?

Potassium permanganate treatment

What happens during the breakdown of ozone?

CO2 and Nascent oxygen is formed

Formation of oxygen and water takes place.

Which of the following is termed as free available chlorine?

Hypochlorous acid, Hypochlorite ions, Molecular chlorine

32 + Mcqs in Disinfection in Environmental Science Page 1 McqOptions

1.	The efficiency of chlorine increase by
A.	Presence of metallic compounds
B.	When the pH of the water increases
C.	When the pH of the water decreases
D.	Turbid water
Answer» D. Turbid water

Discussion

2.	The ozone generators can convert ____ % of feed oxygen into ozone.
A.	1
B.	5
C.	1-4
D.	10
Answer» D. 10

Discussion

3.	For changing the concentration of disinfectant, the disinfecting efficiency is expressed by
A.	C n *t p = Constant
B.	C n/ t p = Constant
C.	C q * Np = Constant
D.	C q / Np = Constant
Answer» B. C n/ t p = Constant

Discussion

4.	Bleaching powder contains ______ of available chlorine.
A.	0.16
B.	0.333
C.	0.666
D.	0.999
Answer» C. 0.666

Discussion

5.	The depth of water while using ultra violet ray treatment for disinfection should be ____
A.	35cm
B.	46cm
C.	28cm
D.	10cm
Answer» E.

Discussion

6.	The amount of hypochlorous acid formed when pH of water is 8 is
A.	95% of total free chlorine
B.	80% of total free chlorine
C.	30% of total free chlorine
D.	5% of total free chlorine
Answer» D. 5% of total free chlorine

Discussion

7.	The presence of metallic compounds in water _______ the efficiency of chlorine.
A.	Decreases
B.	Increases
C.	Slightly decreases
D.	Remains constant
Answer» B. Increases

Discussion

8.	The contact time for disinfection by combined chlorine is
A.	20 minutes
B.	30 minutes
C.	40 minutes
D.	60minutes
Answer» E.

Discussion

9.	_______ is the application of chlorine beyond the stage of the break point.
A.	Plain chlorination
B.	Pre chlorination
C.	Super chlorination
D.	Double chlorination
Answer» D. Double chlorination

Discussion

10.	When turbidity in water increases, the efficiency of chlorine
A.	Decreases
B.	Increases
C.	Slightly increases
D.	Remains constant
Answer» B. Increases

Discussion

11.	At what pH, the E-Coli bacteria will die in the water?
A.	6
B.	7
C.	9
D.	>9.5
Answer» E.

Discussion

12.	The normal dose of chlorine during post chlorination is
A.	0.5-1ppm
B.	0.1-0.2ppm
C.	0.1-0.5ppm
D.	1-2ppm
Answer» C. 0.1-0.5ppm

Discussion

13.	The number of organisms in disinfection process can be expressed by
A.	Cn *t p = Constant
B.	C n/ tp = Constant
C.	C q * Np = Constant
D.	C q / Np = Constant
Answer» D. C q / Np = Constant

Discussion

14.	Ozone is a _______ allotrope of oxygen.
A.	Monoatomic
B.	Diatomic
C.	Triatomic
D.	Polyatomic
Answer» D. Polyatomic

Discussion

15.	The expression loge N1/N = – kt m Where, m is a constant such that m>1 represents
A.	Rate of the kill will remains constant with time
B.	Rate of the kill will increase with time
C.	Rate of the kill will decrease with time
D.	Rate of the kill is directly proportional to time
Answer» C. Rate of the kill will decrease with time

Discussion

16.	When the coefficient of dilution is 1, then which of the following statement is correct?
A.	Time of contact is more important than dosage
B.	The dosage is more important than time of contact
C.	Concentration and time are equally important
D.	Efficiency of dilution decreases.
Answer» D. Efficiency of dilution decreases.

Discussion

17.	The permissible limit of free residual chlorine is
A.	0.02ppm
B.	0.2ppm
C.	1ppm
D.	2ppm
Answer» C. 1ppm

Discussion

18.	Which method of disinfection is mainly used in rural areas?
A.	Boiling method
B.	Excess lime treatment
C.	Potassium permanganate treatment
D.	Silver treatment
Answer» D. Silver treatment

Discussion

19.	Which of the following is most effective in the killing of bacteria present in water?
A.	Nascent oxygen
B.	Chlorine
C.	HOBr
D.	I2
Answer» B. Chlorine

Discussion

20.	State whether the following statement is true or false.Iodine is a better disinfectant to kill virus than hypoiodous acid.
A.	True
B.	False
Answer» C.

Discussion

21.	What happens during the breakdown of ozone?
A.	CO2 is formed
B.	Nascent oxygen is formed
C.	CO2 and Nascent oxygen is formed
D.	Formation of oxygen and water takes place.
Answer» C. CO2 and Nascent oxygen is formed

Discussion

22.	The process of chlorination with hypochlorites is called
A.	Super chlorination
B.	Pre chlorination
C.	Post chlorination
D.	Hypo-chlorination
Answer» E.

Discussion

23.	What is the chemical formula of bleaching powder?
A.	Ca (OCl)2
B.	Ca (OCl)
C.	Ca (OCl)3
D.	CaCl2
Answer» B. Ca (OCl)

Discussion

24.	Which color is formed when orthotolidine is oxidized by chlorine?
A.	Yellow
B.	Orange
C.	Green
D.	Blue
Answer» B. Orange

Discussion

25.	a HIO + b OH- <=> HIO3 + b H2O + b I–. What are the values of a and b respectively in the above equation?
A.	1, 2
B.	1, 3
C.	3, 2
D.	3, 1
Answer» D. 3, 1

Discussion

26.	The contact time for disinfection by free chlorine is
A.	20 minutes
B.	30 minutes
C.	40 minutes
D.	60minutes
Answer» B. 30 minutes

Discussion

27.	Which of the following is termed as free available chlorine?
A.	Hypochlorous acid
B.	Hypochlorite ions
C.	Molecular chlorine
D.	Hypochlorous acid, Hypochlorite ions, Molecular chlorine
Answer» E.

Discussion

28.	State whether the following statement is true or false.The temperature of disinfection is inversely proportional to the killing of organisms.
A.	True
B.	False
Answer» C.

Discussion

29.	The process of removal of excess chlorine from water is
A.	Plain chlorination
B.	Dechlorination
C.	Super chlorination
D.	Double chlorination
Answer» C. Super chlorination

Discussion

30.	Which type of chlorine is represented by the red line as shown in figure?
A.	Free residual chlorine
B.	Ammonia chlorine
C.	Combined residual chlorine
D.	Residual chloramine
Answer» C. Combined residual chlorine

Discussion

31.	Efficiency of dilution decreases rapidly when the coefficient of dilution is
A.	0
B.	1
C.	<1
D.	>1
Answer» E.

Discussion

32.	Consider the following variables.1. Concentration of disinfectant2. Concentration of organisms3. Temperature4. Time of contactDisinfection is the function of which of the following variables?
A.	1, 2
B.	1, 2, 3
C.	1, 2, 3, 4
D.	2, 3, 4
Answer» D. 2, 3, 4

Discussion

Explore topic-wise MCQs in Environmental Science.

The efficiency of chlorine increase by

The ozone generators can convert ____ % of feed oxygen into ozone.

For changing the concentration of disinfectant, the disinfecting efficiency is expressed by

Bleaching powder contains ______ of available chlorine.

The depth of water while using ultra violet ray treatment for disinfection should be ____

The amount of hypochlorous acid formed when pH of water is 8 is

The presence of metallic compounds in water _______ the efficiency of chlorine.

The contact time for disinfection by combined chlorine is

_______ is the application of chlorine beyond the stage of the break point.

When turbidity in water increases, the efficiency of chlorine

At what pH, the E-Coli bacteria will die in the water?

The normal dose of chlorine during post chlorination is

The number of organisms in disinfection process can be expressed by

Ozone is a _______ allotrope of oxygen.

The expression loge N1/N = – kt m Where, m is a constant such that m>1 represents

When the coefficient of dilution is 1, then which of the following statement is correct?

The permissible limit of free residual chlorine is

Which method of disinfection is mainly used in rural areas?

Which of the following is most effective in the killing of bacteria present in water?

State whether the following statement is true or false.Iodine is a better disinfectant to kill virus than hypoiodous acid.

What happens during the breakdown of ozone?

The process of chlorination with hypochlorites is called

What is the chemical formula of bleaching powder?

Which color is formed when orthotolidine is oxidized by chlorine?

a HIO + b OH- <=> HIO3 + b H2O + b I–. What are the values of a and b respectively in the above equation?

The contact time for disinfection by free chlorine is

Which of the following is termed as free available chlorine?

State whether the following statement is true or false.The temperature of disinfection is inversely proportional to the killing of organisms.

The process of removal of excess chlorine from water is

Which type of chlorine is represented by the red line as shown in figure?

Efficiency of dilution decreases rapidly when the coefficient of dilution is

Consider the following variables.1. Concentration of disinfectant2. Concentration of organisms3. Temperature4. Time of contactDisinfection is the function of which of the following variables?