Some multiple-choice questions (MCQs) based on the notes Sterilization
1. Who laid down the general principles of asepsis?
A) Joseph Lister
B) Ignaz Semmelweis
C) Louis Pasteur
D) Hungarian scientist
Answer: D) Hungarian scientist
2. Which of the following terms refers to the process of removing
visible contamination but not necessarily destroying microorganisms?
A) Cleaning
B) Sterilization
C) Disinfection
D) Asepsis
Answer: A) Cleaning
3. What is the primary goal of asepsis?
A) To reduce the microbial population to a safe level
B) To destroy all microorganisms, including spores
C) To prevent contamination of wounds and other sites
D) To inhibit the growth of microorganisms temporarily
Answer: C) To prevent contamination of wounds and other sites
4. Which of the following methods is used for pre-sterilization
cleaning?
A) Dry heat
B) Ultrasonic cleaning
C) Autoclaving
D) Gamma radiation
Answer: B) Ultrasonic cleaning
5. Which category of dental instruments requires sterilization
between uses due to the highest risk of infection transmission?
A) Critical
B) Semi-critical
C) Non-critical
D) Non-sterilizable
Answer: A) Critical
6. What is the most common and effective method of sterilization?
A) Chemical sterilization
B) Radiation
C) Heat sterilization
D) Filtration
Answer: C) Heat sterilization
7. What is the principle behind ultrasonic cleaning?
A) High-pressure jets of water
B) Conversion of electrical energy into vibratory sound waves
C) Exposure to ultraviolet light
D) Use of high-temperature air
Answer: B) Conversion of electrical energy into vibratory sound waves
8. Which of the following is a method of chemical disinfection?
A) Dry heat
B) Hydrogen peroxide
C) Hot air oven
D) Filtration
Answer: B) Hydrogen peroxide
9. Which type of heat sterilization causes protein denaturation and
coagulation?
A) Dry heat
B) Moist heat
C) Filtration
D) Gas sterilization
Answer: B) Moist heat
10. Which of the following is a commonly used biological indicator
for the control of autoclave sterilization?
A) Bacillus subtilis
B) Geobacillus stearothermophilus
C) Clostridium tetani
D) Escherichia coli
Answer: B) Geobacillus stearothermophilus
11. What is the main advantage of ethylene oxide (ETO) sterilization?
A) It is cost-effective
B) It can sterilize heat-sensitive equipment
C) It is a rapid sterilization method
D) It requires no special precautions
Answer: B) It can sterilize heat-sensitive equipment
12. What is the primary disadvantage of using ethylene oxide for
sterilization?
A) It is inexpensive
B) The cycle time is lengthy
C) It is ineffective against spores
D) It cannot sterilize plastics
Answer: B) The cycle time is lengthy
13. Which of the following is NOT a method of sterilization by heat?
A) Autoclaving
B) Hot air oven
C) Glass beads sterilizer
D) Filtration
Answer: D) Filtration
14. Which of the following is a key factor influencing sterilization by
heat?
A) Type of microorganism
B) Number of microorganisms present
C) Duration of exposure to heat
D) All of the above
Answer: D) All of the above
15. In which method of sterilization are the spores of Bacillus subtilis
used as a test organism?
A) Dry heat sterilization
B) Autoclave sterilization
C) Glass beads sterilization
D) Ethylene oxide sterilization
Answer: B) Autoclave sterilization
Sure! Here are 20 more multiple-choice questions (MCQs) based on your
notes:
1. Which of the following is the process of removing pathogenic
microorganisms to make an object safe to handle?
A) Sanitizing
B) Decontamination
C) Disinfection
D) Sterilization
Answer: B) Decontamination
2. The process that eliminates defined pathogens but does not affect
all microorganisms is known as:
A) Disinfection
B) Sterilization
C) Asepsis
D) Sanitization
Answer: A) Disinfection
3. The term used to describe methods that prevent contamination of
wounds and other sites by ensuring only sterile objects come into
contact is:
A) Disinfection
B) Antisepsis
C) Asepsis
D) Cleaning
Answer: C) Asepsis
4. What is the main purpose of the ultrasonic cleaning method?
A) To remove debris using high-pressure jets
B) To use vibratory sound waves to clean instruments
C) To heat up the instruments for sterilization
D) To wash instruments manually
Answer: B) To use vibratory sound waves to clean instruments
5. The removal of all microorganisms from an object, including
spores, is called:
A) Sterilization
B) Disinfection
C) Cleaning
D) Antisepsis
Answer: A) Sterilization
6. What is the key characteristic of low-level disinfection?
A) Inactivates bacterial spores
B) Only destroys vegetative bacteria
C) It is effective against viruses
D) It completely sterilizes objects
Answer: B) Only destroys vegetative bacteria
7. Which of the following is a chemical disinfectant that is a phenol
derivative?
A) Chlorhexidine
B) Formaldehyde
C) Cresol
D) Hydrogen peroxide
Answer: C) Cresol
8. The process of using steam under pressure to sterilize materials is
known as:
A) Autoclaving
B) Dry heat sterilization
C) Filtration
D) Radiation
Answer: A) Autoclaving
9. Which of the following sterilization methods uses ionizing
radiation?
A) UV light
B) Gamma rays
C) Hot air oven
D) Ethylene oxide
Answer: B) Gamma rays
10. What is the main principle behind the use of dry heat for
sterilization?
A) Moisture facilitates microorganism destruction
B) Heat causes protein denaturation and dehydration of organisms
C) High humidity is required for effectiveness
D) It uses short-range UV light for sterilization
Answer: B) Heat causes protein denaturation and dehydration of
organisms
11. Which of the following is a limitation of using ultraviolet (UV)
light for sterilization?
A) It has high penetrating power
B) It is effective for large volumes
C) It cannot penetrate solid materials
D) It is effective for sterilizing liquids
Answer: C) It cannot penetrate solid materials
12. Which of the following statements is true about ethylene oxide
(ETO) sterilization?
A) It is only used for plastics and rubbers
B) It works by alkylating nucleic acids of microorganisms
C) It is not effective for sterilizing heat-sensitive items
D) It requires exposure to high temperatures for sterilization
Answer: B) It works by alkylating nucleic acids of microorganisms
13. In which method is the temperature typically set to 121°C for
sterilization?
A) Hot air oven
B) Autoclaving
C) Glass beads sterilizer
D) Filtration
Answer: B) Autoclaving
14. Which of the following sterilization methods uses gas to sterilize
sensitive equipment?
A) Hot air oven
B) Ethylene oxide sterilization
C) Autoclaving
D) Dry heat sterilization
Answer: B) Ethylene oxide sterilization
15. Which type of radiation is commonly used for sterilization in
commercial plants?
A) Infrared radiation
B) Gamma radiation
C) Ultraviolet radiation
D) X-rays
Answer: B) Gamma radiation
16. In which of the following sterilization processes are biological
indicators used to test efficacy?
A) Filtration
B) Dry heat sterilization
C) Autoclaving
D) Ethylene oxide sterilization
Answer: C) Autoclaving
17. The primary function of an autoclave is to:
A) Use dry heat to sterilize instruments
B) Destroy all microorganisms, including spores, through high-pressure
steam
C) Use UV light to disinfect surfaces
D) Use gas to sterilize heat-sensitive items
Answer: B) Destroy all microorganisms, including spores, through high-
pressure steam
18. Which of the following is NOT a factor influencing sterilization
by heat?
A) Time and temperature
B) The number of microorganisms present
C) The presence of organic material
D) The type of radiation used
Answer: D) The type of radiation used
19. Which of the following is NOT used as a method of sterilization
by heat?
A) Autoclaving
B) Hot air oven
C) Filtration
D) Glass beads sterilizer
Answer: C) Filtration
20. What is the main limitation of using the glass beads sterilizer?
A) It is not effective for small instruments
B) It cannot reach high enough temperatures
C) It is not suitable for delicate instruments
D) It requires long exposure times
Answer: C) It is not suitable for delicate instruments
Here are 20 multiple-choice questions (MCQs) based on the detailed
information you provided:
1. What is the primary advantage of using ethylene oxide (ETO)
sterilization?
A) It is quick and inexpensive
B) It can sterilize heat or moisture-sensitive medical equipment
C) It requires no special precautions
D) It works best for metals
Answer: B) It can sterilize heat or moisture-sensitive medical equipment
2. What is the disadvantage of using ethylene oxide sterilization?
A) It is very fast
B) It requires long cycle times
C) It is inexpensive
D) It has no potential hazards
Answer: B) It requires long cycle times
3. What is the key principle behind aseptic storage of sterile items?
A) Instruments should be stored in direct sunlight
B) Instruments should be kept in a cool, dry area away from contaminants
C) Instruments should be stored in open areas for easy access
D) Instruments should be exposed to constant humidity
Answer: B) Instruments should be kept in a cool, dry area away from
contaminants
4. What should be done to prevent contamination of sterile packs
during storage?
A) Sterile packs should be handled as much as possible
B) Sterile packs should be allowed to cool before storage
C) Sterile packs should be stored in open areas
D) Sterile packs should not be wrapped
Answer: B) Sterile packs should be allowed to cool before storage
5. What is the correct procedure for storing sterilized materials to
avoid contamination from pests?
A) Materials should be stored directly on the floor
B) Store materials at least 8” off the floor and 18” from the ceiling
C) Store materials in direct sunlight
D) Store materials in open containers
Answer: B) Store materials at least 8” off the floor and 18” from the
ceiling
6. Which chemical is used in the fumigation of an operating theatre?
A) Chlorine
B) Potassium permanganate
C) Formaldehyde
D) Hydrogen peroxide
Answer: C) Formaldehyde
7. What is the minimum relative humidity required for effective
fumigation in an operating theatre?
A) 40%
B) 50%
C) 60%
D) 70%
Answer: D) 70%
8. Which of the following is an aldehyde compound used for
disinfection and sterilization?
A) Formaldehyde
B) Alcohol
C) Iodophor
D) Chlorhexidine
Answer: A) Formaldehyde
9. Which alcohol is preferred for clinical use due to its better fat-
solvent properties and bactericidal action?
A) Methanol
B) Propanol
C) Isopropyl alcohol
D) Ethanol
Answer: C) Isopropyl alcohol
10. What is the primary function of iodophor compounds in
sterilization?
A) They oxidize the bacteria
B) They release iodine to destroy microorganisms
C) They form a protective barrier around instruments
D) They neutralize toxins
Answer: B) They release iodine to destroy microorganisms
11. Which of the following is the most commonly used biguanide
compound for antiseptic purposes?
A) Chlorhexidine
B) Glutaraldehyde
C) Povidone-iodine
D) Hydrogen peroxide
Answer: A) Chlorhexidine
12. What is a major advantage of using hydrogen peroxide in
sterilization?
A) It is inexpensive and easy to use
B) It has a short cycle time for sterilization
C) It is non-toxic
D) It is effective at low concentrations
Answer: B) It has a short cycle time for sterilization
13. In which zone should personnel engage in operating theatre
activities?
A) Outer zone
B) Clean zone
C) Restricted access zone
D) Aseptic zone
Answer: C) Restricted access zone
14. Which handwashing procedure is required before any invasive or
surgical procedure requiring sterile gloves?
A) Social hand washing
B) Clinical hand washing
C) Surgical hand washing
D) Emergency hand washing
Answer: C) Surgical hand washing
15. What is the main purpose of surgical scrubbing before a
procedure?
A) To remove all microorganisms from the hands
B) To remove dirt and grime from the hands
C) To reduce moisture on the hands
D) To prepare hands for wearing gloves
Answer: A) To remove all microorganisms from the hands
16. Which method of sterilization uses high-pressure steam to destroy
all microbial life?
A) Dry heat
B) Autoclaving
C) Gas sterilization
D) Filtration
Answer: B) Autoclaving
17. What is the main factor that influences the steam sterilization
process in an autoclave?
A) Type of gas used
B) Temperature and time
C) Humidity levels
D) Size of the autoclave
Answer: B) Temperature and time
18. In the autoclave sterilization process, what is the purpose of the
"heating phase"?
A) To remove air from the chamber
B) To bring the steam to the correct temperature
C) To dry the instruments
D) To check the gauges
Answer: B) To bring the steam to the correct temperature
19. Which of the following is NOT a common cause of failure in
autoclave sterilization?
A) Poor quality steam
B) Failure to remove air
C) Faulty gauges and timing
D) Too many sterilization cycles
Answer: D) Too many sterilization cycles
20. What is the minimum sterilization time required for instruments
in a downward displacement autoclave at 131°C?
A) 15 minutes
B) 50 minutes
C) 60 minutes
D) 120 minutes
Answer: B) 50 minutes
Here are 10 more multiple-choice questions based on the information you
provided:
21. What is the primary method used to sterilize surgical instruments
and dressings in an autoclave?
A) Chemical disinfection
B) Gas sterilization
C) Steam sterilization under pressure
D) Filtration
Answer: C) Steam sterilization under pressure
22. What is the purpose of the "drying and cooling phase" in the
steam sterilization process?
A) To increase the temperature
B) To remove air from the chamber
C) To ensure that the sterilized items are dry and safe for use
D) To monitor the steam quality
Answer: C) To ensure that the sterilized items are dry and safe for use
23. What type of chemical disinfectant is glutaraldehyde?
A) High-level disinfectant
B) Low-level disinfectant
C) Intermediate-level disinfectant
D) Antiseptic
Answer: A) High-level disinfectant
24. How does formaldehyde primarily act as a disinfectant?
A) By denaturing proteins
B) By disrupting cell membranes
C) By oxidizing microorganisms
D) By forming a protective coating
Answer: A) By denaturing proteins
25. Which of the following is a major disadvantage of using
glutaraldehyde for sterilization?
A) It has a long exposure time for sterilization
B) It is too expensive to use in large quantities
C) It is effective only at very low concentrations
D) It is too volatile for safe use
Answer: A) It has a long exposure time for sterilization
26. What is the primary use of hydrogen peroxide in sterilization?
A) Disinfection of equipment exposed to organic materials
B) Sterilization of heat-sensitive instruments
C) Deodorizing operating rooms
D) Cleaning surgical wounds
Answer: B) Sterilization of heat-sensitive instruments
27. Which of the following methods is commonly used for sterilizing
items that are sensitive to heat or moisture?
A) Dry heat
B) Ethylene oxide (ETO) gas
C) Autoclaving
D) Boiling water
Answer: B) Ethylene oxide (ETO) gas
28. What is one of the primary safety concerns when using ethylene
oxide gas for sterilization?
A) It is highly flammable and potentially explosive
B) It is non-toxic to humans
C) It is ineffective in sterilizing plastics
D) It can cause severe corrosion of instruments
Answer: A) It is highly flammable and potentially explosive
29. In which zone should the operating theatre staff, wearing sterile
attire, operate?
A) Aseptic or operating zone
B) Clean zone
C) Outer zone
D) Restricted access zone
Answer: A) Aseptic or operating zone
30. What is the primary purpose of using a "social hand wash"?
A) To reduce microbial contamination before surgery
B) To clean hands after contact with patients or contaminated items
C) To prepare hands for invasive procedures
D) To wash hands before contact with sterile equipment
Answer: B) To clean hands after contact with patients or contaminated
items
Here are 10 more multiple-choice questions based on the new information
you've provided:
31. What is the primary purpose of autoclave tape on a sterilized
package?
A) To indicate the contents of the package
B) To show the package has been through a sterilization cycle
C) To label the expiration date
D) To ensure the package is not contaminated
Answer: B) To show the package has been through a sterilization cycle
32. What should be done to sterile packages before storing them to
avoid contamination?
A) Allow them to cool before storage
B) Store them immediately to prevent loss of sterility
C) Wrap them in plastic for extra protection
D) Spray them with disinfectant
Answer: A) Allow them to cool before storage
33. What is the shelf life of sterile packages based on?
A) The type of sterilizer used
B) The number of times the package has been sterilized
C) The wrapping material used and how it is wrapped
D) The temperature at which the sterilized items are stored
Answer: C) The wrapping material used and how it is wrapped
34. How often should biological indicators be used to monitor the
effectiveness of sterilizers?
A) Once a day
B) Once a week
C) Once a month
D) After each sterilization cycle
Answer: B) Once a week
35. What is the main disadvantage of using the flash sterilizer (high-
speed sterilizer)?
A) It is only effective for unwrapped instruments
B) It cannot sterilize heat-sensitive items
C) It is time-consuming
D) It requires high pressure
Answer: A) It is only effective for unwrapped instruments
36. Which of the following is a common disadvantage of ethylene
oxide (EO) sterilization?
A) It is non-toxic
B) It can cause damage to delicate instruments
C) It is a lengthy process with long exposure and aeration times
D) It is the most cost-effective sterilization method
Answer: C) It is a lengthy process with long exposure and aeration times
37. What is the recommended temperature range for sterilizing with
ethylene oxide (EO)?
A) 80ºC to 100ºC
B) 21ºC to 60ºC
C) 100ºC to 120ºC
D) 120ºC to 135ºC
Answer: B) 21ºC to 60ºC
38. Which sterilization method uses gamma radiation from a Cobalt
60 source?
A) Ethylene oxide gas sterilization
B) Plasma sterilization
C) Ultraviolet light sterilization
D) Gamma radiation sterilization
Answer: D) Gamma radiation sterilization
39. Which of the following methods is used to sterilize delicate
instruments that cannot withstand high temperatures?
A) Steam autoclaving
B) Plasma sterilization (Sterrad)
C) Flash sterilization
D) Dry heat sterilization
Answer: B) Plasma sterilization (Sterrad)
40. What is a key precaution when using ethylene oxide (EO) for
sterilization?
A) It should only be used for heat-sensitive materials
B) It can be safely used without aeration
C) It can be used without cleaning the instruments beforehand
D) It has no toxic effects on personnel
Answer: A) It should only be used for heat-sensitive materials
11. What is the primary purpose of sterilization in healthcare?
A) To make instruments look new
B) To eliminate harmful microorganisms from medical instruments
C) To increase the shelf life of medical supplies
D) To sanitize instruments for immediate use
Answer: B) To eliminate harmful microorganisms from medical
instruments
12. How should sterile packages be handled to minimize
contamination?
A) They should be handled as much as possible
B) They should be handled only by CSSD personnel
C) They should be stored in closed cabinets
D) They should be stored in sealed plastic bags
Answer: B) They should be handled only by CSSD personnel
13. What must be labeled on each sterilized package?
A) Manufacturer's name
B) Sterilization method used
C) Processing date, autoclave used, and load number
D) Name of the person who packed the items
Answer: C) Processing date, autoclave used, and load number
14. What type of sterilization is best for heat-sensitive materials?
A) Steam autoclaving
B) Gamma radiation
C) Ethylene oxide (EO) gas sterilization
D) Dry heat sterilization
Answer: C) Ethylene oxide (EO) gas sterilization
15. Which of the following is a disadvantage of gamma radiation
sterilization?
A) It is non-toxic
B) It requires high temperatures
C) It is an expensive process
D) It cannot be used for heat-sensitive materials
Answer: C) It is an expensive process
16. What must be done before instruments are exposed to ethylene
oxide for sterilization?
A) They should be thoroughly cleaned
B) They should be heated to 120ºC
C) They should be wrapped in plastic
D) They should be rinsed with alcohol
Answer: A) They should be thoroughly cleaned
17. How can the effectiveness of an autoclave be tested mechanically?
A) Using biological indicators
B) Using charts and gauges monitored by a Biomed Engineer
C) Using chemical test strips
D) Using a Bowie Dick Test Pack
Answer: B) Using charts and gauges monitored by a Biomed Engineer
18. What is a key requirement for proper storage of sterile packages?
A) Sterile packages should be stored in closed drawers
B) They should be stored on open shelves, 8 inches off the floor
C) They should be stored in sealed bags to prevent exposure to air
D) They should be kept in a refrigerator
Answer: B) They should be stored on open shelves, 8 inches off the floor
19. What is the purpose of a Bowie Dick Test Pack?
A) To verify the sterilizer's pressure
B) To ensure the correct temperature was reached inside the autoclave
C) To test for the penetration of steam into the pack
D) To monitor the biological effectiveness of sterilization
Answer: C) To test for the penetration of steam into the pack
20. What does the term "shelf life" of a sterile package refer to?
A) The length of time the sterilization process takes
B) The duration the package remains sterile if stored properly
C) The time it takes for a package to be packed
D) The time required for the autoclave cycle
Answer: B) The duration the package remains sterile if stored properly
21. Which microorganisms are used for biological testing of
autoclaves?
A) E. coli
B) Bacillus stearothermophilus
C) Geobacillus thermophilus
D) Staphylococcus aureus
Answer: B) Bacillus stearothermophilus
22. How should sterile items be stored to avoid contamination?
A) Stored in sealed plastic bags
B) Stored in an area with restricted traffic
C) Stored near high-traffic areas for easy access
D) Stored under direct sunlight
Answer: B) Stored in an area with restricted traffic
23. Which sterilization method is best for items that cannot withstand
high heat or pressure?
A) Plasma sterilization (Sterrad)
B) Steam autoclaving
C) Flash sterilization
D) Dry heat sterilization
Answer: A) Plasma sterilization (Sterrad)
24. What temperature is typically required for high-speed
sterilization (flash sterilizer)?
A) 120ºC (248ºF)
B) 132ºC (270ºF)
C) 150ºC (302ºF)
D) 200ºC (392ºF)
Answer: B) 132ºC (270ºF)
25. What is a major disadvantage of ethylene oxide sterilization?
A) It is harmful to plastics
B) It requires long exposure times and aeration periods
C) It is only effective for hard surfaces
D) It cannot be used for heat-sensitive materials
Answer: B) It requires long exposure times and aeration periods
26. Which sterilization method is used for non-heat-stable items such
as certain plastics?
A) Ethylene oxide sterilization
B) Flash sterilization
C) Steam autoclaving
D) Dry heat sterilization
Answer: A) Ethylene oxide sterilization
27. Which test verifies that steam has penetrated a sterilization pack?
A) Chemical indicator strip
B) Biological indicator
C) Bowie Dick Test
D) Mechanical indicator
Answer: C) Bowie Dick Test
28. How often should a biological test be performed in a sterilizer?
A) Daily
B) Weekly
C) Monthly
D) Annually
Answer: B) Weekly
29. Which of the following is a limitation of flash sterilization?
A) It cannot sterilize unwrapped instruments
B) It is effective for heat-sensitive materials
C) It requires a shorter sterilization cycle
D) It is not recommended for implantable devices
Answer: D) It is not recommended for implantable devices
30. Which sterilization method uses ultraviolet light for surface
sterilization?
A) Ethylene oxide sterilization
B) Gamma radiation sterilization
C) Ultraviolet light sterilization
D) Plasma sterilization
Answer: C) Ultraviolet light sterilization
