Sterilization and Disinfection - Numerical Applications
Q. How long should items be exposed to ethylene oxide gas for effective sterilization?
-
A.
1 hour
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B.
4 hours
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C.
8 hours
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D.
12 hours
Solution
Items should be exposed to ethylene oxide gas for at least 8 hours for effective sterilization.
Correct Answer: C — 8 hours
Q. How many minutes of exposure to 160°C dry heat is required for sterilization?
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A.
30 minutes
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B.
60 minutes
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C.
90 minutes
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D.
120 minutes
Solution
Sterilization at 160°C dry heat typically requires 60 minutes of exposure.
Correct Answer: B — 60 minutes
Q. If a disinfectant has a contact time of 10 minutes, how many times can it be used in an hour?
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A.
4 times
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B.
5 times
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C.
6 times
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D.
7 times
Solution
If the contact time is 10 minutes, it can be used 6 times in an hour.
Correct Answer: B — 5 times
Q. If a solution is diluted from 1000 ppm to 100 ppm, what is the dilution factor?
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A.
1:10
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B.
1:5
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C.
1:20
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D.
1:50
Solution
The dilution factor is 1:10, as the concentration is reduced by a factor of 10.
Correct Answer: A — 1:10
Q. If a sterilization cycle takes 30 minutes at 121°C, how long would it take at 134°C?
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A.
10 minutes
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B.
15 minutes
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C.
20 minutes
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D.
25 minutes
Solution
At 134°C, the sterilization time can be reduced to approximately 20 minutes due to the increased temperature.
Correct Answer: C — 20 minutes
Q. What is the appropriate concentration of hydrogen peroxide for high-level disinfection?
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A.
3%
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B.
6%
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C.
30%
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D.
50%
Solution
A concentration of 30% hydrogen peroxide is appropriate for high-level disinfection.
Correct Answer: C — 30%
Q. What is the D-value for a microorganism if it takes 5 minutes to reduce the population by 90% at 121°C?
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A.
1 minute
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B.
2 minutes
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C.
5 minutes
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D.
10 minutes
Solution
The D-value is the time required to reduce the microbial population by 90%, which in this case is 5 minutes.
Correct Answer: C — 5 minutes
Q. What is the minimum effective concentration of ethanol for disinfection?
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A.
50%
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B.
70%
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C.
90%
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D.
100%
Solution
70% ethanol is the minimum effective concentration for disinfection as it allows for better penetration and denaturation of proteins.
Correct Answer: B — 70%
Q. What is the minimum effective temperature for autoclaving to ensure sterilization?
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A.
100°C
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B.
121°C
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C.
130°C
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D.
150°C
Solution
The minimum effective temperature for autoclaving to ensure sterilization is 121°C.
Correct Answer: B — 121°C
Q. What is the recommended contact time for a 10% bleach solution to effectively disinfect surfaces?
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A.
1 minute
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B.
5 minutes
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C.
10 minutes
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D.
15 minutes
Solution
A 10% bleach solution is recommended to be in contact with surfaces for at least 5 minutes for effective disinfection.
Correct Answer: B — 5 minutes
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