# Sterilization MCQ Questions & Answers

Sterilization MCQs : This section focuses on the "Sterilization". These Multiple Choice Questions (MCQs) should be practiced to improve the Sterilization skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

The sterilization method depends

B. volume and feed rate
C. Both A and B
D. None of the above

Question 2

The specific death rate of an organism can be expressed as

A. ln 2/D
B. D/ln2
C. D.ln2
D. 2.0.3/ln2

Question 3

The interception efficiency can be expressed as (where dp is the particle diameter and Dc cylindrical collection diameter)

A. dp/Dc
B. dp x Dc
C. dp/Dc x 100
D. dpDc/100

Question 4

The relationship between the del factor, temperature and time is given as

A. Δ = A.t. e^-E/RT
B. Δ = 1/(A.t. e^-E/RT)
C. Δ = A.t. e^E/RT
D. Δ = A.t.T

Question 5

The del factor (Δ) increases as the final number of cells

A. decreases
B. increases
C. zero
D. constant

Question 6

The overall del factor (Δ) may be represented as

A. Δoverall = Δheating + Δholding- Δcooling
B. Δoverall = Δheating + Δholding+ Δcooling
C. Δoverall = Δheating - Δholding+ Δcooling
D. Δoverall = Δheating - Δholding- Δcooling

Question 7

The filter material used for air filtration system is/are

A. glass wool
B. glass fibre
C. norite
D. All of the above

Question 8

The deviation from ideal plug flow due to axial mixing can be described by the

A. dispersion model
B. Langmuir model
C. Friedlander model
D. Pasceri model

Question 9

The collection efficiency by diffusion increases with

A. decreasing particle size
B. decreasing air velocity
C. Both A and B
D. increasing particle size

Question 10

Glass fibers are favorable as a filter medium because they give a

A. lower pressure drop and are less liable to wetting or combustion
B. more pressure drop and are less liable to wetting or combustion
C. lower pressure drop and are more liable to wetting or combustion
D. more pressure drop and are more liable to wetting or combustion

Question 11

The collection efficiency by interception increases with the

A. increasing particle diameter
B. increasing air flow velocity
C. Both A and B
D. increasing particle size

Question 12

For indirect heating, the plate and frame heat exchanger is generally more effective than the shell and tube heat transfer due to its

A. larger heat transfer area
B. smaller heat transfer area
C. lesser cost
D. more number of plates

Question 13

The mechanism of air filtration in fibrous filter is

A. electrostatic attraction
B. impaction
C. interception
D. All of the above

Question 14

If the packing density (α) is defined as the volume of the fiber unit volume of filter bed, the velocity within the filter void space is equal to (where V is velocity in fluid void space and V0 is undisturbed fluid velocity)

A. V = V0/(1-α)
B. V-V0 = 1 - α
C. V = V0(1 - α)
D. V = V0/(1 + α)

Question 15

For the turbulent flow, the dispersion coefficient is correlated as a function of

A. Reynolds number
B. Sherwood number
C. Schmidt number
D. Grashof number

Question 16

In sterilization process, spore of which of the following organism is considered as control?

A. Bacillus subtilis
B. Clostridium botulinum
C. Bacillus stearothermophilus
D. Aspergillus niger

Question 17

Analogus to the molecular diffusion, the x-directional flux of microorganisms suspended in a medium due to the axial mixing can be represented as (where Jn is flux component 'n', cn is concentration of'n')

A. Jn = -dcn/dx
B. Jn = dcn/dx
C. Jn = -D dcn/dx
D. Jn = D dcn/dx

Question 18

The typical size of particles collected by diffusion mechanism is

A. <0.25μm
B. <0.5μm
C. <0.75μm
D. <1μm

Question 19

The X90 value for a filtration system is

A. the time required to reduce microbial population by 90%
B. the time required to traverse survivor curve by one log cycle.
C. the depth required to reduce population by 90%
D. the depth of the filter required to reduce population by 99%

Question 20

The value of K

A. increases with increase in air velocity
B. decreases with increase in air velocity
C. increases to an optimum with increase in air velocity and decreases on further increase of air velocity
D. None of the above

Question 21

Model proposed by the Friedlander, correlating the air filtration efficiency by impaction can be expressed as (where NSt is the Stokes number)

A. ηimp = 0.075NSt^1.2
B. ηimp = 0.75NSt^1.2
C. ηimp = 0.25NSt^1.2
D. ηimp = 0.025NSt^1.2

Question 22

The collection efficiency by impaction increases with

A. increasing particle diameter
B. increasing air flow velocity
C. Both A and B
D. increasing particle size

Question 23

The efficiency of fibrous filter by combined mechanism is given by(where ηimp,ηint,ηdif are the efficiencies by impaction, interception and diffusion respectively)

A. 1 - ηimpηintηdif
B. 1 - (1 - ηimp)(1 - ηint)( 1 - ηdif)
C. 1 - ( ηimpηint/ηdif)
D. None of the above

Question 24

The heat conduction in dry air is

A. less rapid than in steam
B. more rapid than in steam
C. similar to steam
D. None of the above

Question 25

For laminar flow of Newtonian fluid through a smooth round pipe, the ratio of average fluid velocity to the maximum velocity is

A. 0.5
B. 0.75
C. 0.87
D. 0.37

Question 26

Model proposed by the Friedlander, correlating the air filtration efficiency by impaction can be expressed as (where NSt is the Stokes number)

A. ηimp = 0.075NSt1.2
B. ηimp = 0.75NSt1.2
C. ηimp = 0.25NSt1.2
D. ηimp = 0.025NSt1.2

Question 27

Sterilization can be carried out by

A. heat
C. chemical agents
D. all of these

Question 28

The collection efficiency by diffusion increases with

A. decreasing particle size
B. decreasing air velocity
C. both (a) and (b)
D. increasing particle size

Question 29

The collection efficiency by impaction increases with

A. increasing particle diameter
B. increasing air flow velocity
C. both (a) and (b)
D. increasing particle size

Question 30

The collection efficiency by interception increases with the

A. increasing particle diameter
B. increasing air flow velocity
C. both (a) and (b)
D. increasing particle size

Question 31

The collection efficiency by the inertial impaction mechanism is the function of

A. Stokes and Reynolds number
B. Stokes and Schmidt number
C. Grashoff and Reynolds number
D. Stokes and Grashof number

Question 32

The destruction of microorganisms by steam may be described as

A. first order chemical reaction
B. zero order chemical reaction
C. second order chemical reaction
D. none of these

Question 33

The heat conduction in dry air is

A. less rapid than in steam
B. more rapid than in steam
C. similar to steam
D. none of these

Question 34

The heated medium passes through a holding section, which is usually maintained in

B. isothermal conditions
C. isotropic conditions
D. isobaric conditions

Question 35

The highest temperature which appears to be feasible for batch sterilization is

A. 121°C
B. 100°C
C. 105°C
D. 130°C

Question 36

The K used in the equation for X10=2.303/K depends upon

A. nature of the filter material
B. linear velocity of the air passing through filter
C. both (a) and (b)
D. thickness of the filter

Question 37

The mechanical means of accomplishing sterilization of fermentation media/equipment is

A. ultrasonic
C. chemical agents
D. none of these

Question 38

The mechanism of air filtration in fibrous filter is

A. electrostatic attraction
B. impaction
C. interception
D. all of these

Question 39

The moist heat is more effective than the dry heat because the intrinsic heat resistance of vegetative cells is greatly

A. increased in a dry state
B. decreased in a dry state
C. increased in a wet state
D. decreased in a wet state

Question 40

The radius of the filter with a depth of 14 cm required for a volumetric airflow rate of 10 m3/min is approximately

A. 1.6 m
B. 0.6 m
C. 3
D. 6 m

Question 41

The reduction of number of cells from 1010 to one will result into the del factor (Δ) of

A. 1
B. 10
C. 23
D. 103

Question 42

The relationship between the del factor, temperature and time is given as

A. Δ = A.t. e-E/RT
B. Δ = 1/(A.t. e-E/RT)
C. Δ = A.t. eE/RT
D. Δ = A.t.T

Question 43

The sterilization method depends

B. volume and feed rate
C. both (a) and (b)
D. none of these

Question 44

The value of K

A. increases with increase in air velocity
B. decreases with increase in air velocity
C. increases to an optimum with increase in air velocity and decreases on further increase of air velocity
D. none of these

Question 45

Typical aeration rates for aerobic fermentation are

A. 0 - 0.5 vvm
B. 0.5 - 1.0 vvm
C. 1.0 - 1.5 vvm
D. 1.5 - 2.0 vvm

Question 46

_______ is the quickest way to sterilize solutions without heating.

A. Filtration
B. Chemical method of sterilization
C. Steam Sterilization
D. Chlorine dioxide gas

Question 47

_______ is used for sterilizing metallic devices like needles, scalpels.

A. Flaming
B. Incineration
C. Hot air oven
D. Steam

Question 48

____________ is used for sterilizing inoculating loops.

A. Flaming
B. Incineration
C. Hot air oven
D. Steam

Question 49

Does sterilization kill viruses?

A. TRUE
B. FALSE

Question 50

The sterilization of ________ is generally carried out by retorts.

A. low carbohydrate foods
B. low acid foods
C. high acid foods
D. medium acid foods

Question 51

Where should a sterilization indicator placed in an autoclave?

A. At the center
B. Close to lid of the autoclave
C. Sides of the autoclave
D. Anywhere inside the autoclave

Question 52

Which of the following is target microbe in commercial sterilization?

A. Pseudomonas aeruginosa
B. Bacillus anthracis
C. Salmonella typhi
D. Clostridium botulinum