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Multiple choice question for engineering

Set 1

1. Rheology of food in the food processing industry is how the food is affected when _____ is applied.
a) Pressure
b) Butter
c) None of the mentioned
d) All of the mentioned

View Answer

Answer: a [Reason:] Rheology of food in the food processing industry is how the food is affected when Pressure is applied.

2. Statement 1: Starch is _____ as its viscosity decreases with increase in shear stress.
Statement 2: Bingham plastics follow Newton’s law of viscosity at low shears.
a) Bingham, False
b) Dilatant, True
c) Pseudo plastic, False
d) Newtonian fluid, True

View Answer

Answer: c [Reason:] Starch is Pseudo plastic as its viscosity decreases with increase in shear stress. Bingham plastics follow Newton’s law of viscosity at high shears. At low shears, they’ve infinite viscosity.

3. Statement 1: Blood is a _____
Statement 2: Thixotropic fluids are fluids whose viscosity decreases when subjected to shear stress initially but eventually with time, the viscosity increases.
a) Newtonian fluid, False
b) Rheopectic, True
c) Pseudo plastic, False
d) Casson plastic, True

View Answer

Answer: d [Reason:] Blood is a Casson plastic. . At low shears, they’ve infinite viscosity. At high shears, its viscosity decreases with increase in shear. Statement 2 is true.

4. Which of the flowing is true about two-parameter model?
a) It is also called as Ostwald-de Waele Model
b) The equation pertaining to it is τ=Kγn
c) These equations pertain to Newtonian, dilatant and pseudo plastic fluids
d) All of the mentioned

View Answer

Answer: d [Reason:] All the given statements about two-parameter model are true.

5. Statement 1: Apparent viscosity μ_a is related to shear stress (τ) and shear strain (γ) as μ_a= τ/γ .
Statement 2: The equation τ=Kγn becomes μ_a= τ/γ = Kγ(n-1) .
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Both the statements are true.

6. Statement 1: In μ_a= τ/γ = Kγ(n-1) , n = consistency index and K is the flow behaviour index.
Statement 2: n= 1 for Newtonian fluids, n<1 for dilatant fluids and n>1 for pseudo plastic fluids.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: c [Reason:] Both the statements are false. K = consistency index and n is the flow behaviour index. n is greater than 1 for dilatant fluids and n is less than 1 for pseudo plastic fluids.

7. Statement 1: Considering the equation, μ_a= τ/γ = Kγ(n-1) , for pseudo plastic fluids, n<1 and they’re called Shear thinning liquids and dilatant fluids are called Shear thickening liquids as n>1.
Statement 2: Cooked starch solution is a Shear thinning liquid and dairy cream is a Shear thickening liquid.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: a [Reason:] Statement 1 is true. But, cooked starch solution is a Shear thickening liquid and dairy cream is a Shear thinning liquid.

8. Which of the following is a name of an actual viscometer?
a) Capillary tube
b) Plate and Cone
c) Coaxial Cylinder
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned, Capillary tube, Plate and Cone and Coaxial Cylinder are all names of viscometers.

9. Statement 1: Brookfield viscometer is an example of Coaxial Cylinder Viscometer.
Statement 2: Working principle of a Brookfield viscometer: Two coaxial cylinders. Liquid is filled in between them. The viscosity produces torque which is directly proportional to the shear stress.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Both the statements pertaining to Brookfield viscometer are true.

10. Statement 1: Brookfield viscometer is very robust, is supported by software and even shows values of K and n, but, sometimes particles suspended in the fluid cause problems.
Statement 2: Drawbacks of plate and cone viscometer: edge-effects, turbulence and temperature effects.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Both the statements pertaining to viscometers are true.

Set 2

1. Sedimentation and centrifugation involves two miscible phases.
a) True
b) False

View Answer

Answer: b [Reason:] Sedimentation and centrifugation involves two immiscible phases.

2. Which of the following does the terminal velocity of a particle NOT depend on?
a) Density of fluid and particle
b) Shape of the particle
c) Viscosity of the fluid
d) None of the mentioned

View Answer

Answer: d [Reason:] The terminal velocity of a particle depends on all the mentioned factors.

3. With respect to Sedimentation, the boundary between the thick suspension and solids will be decreasing and that between the between the clear liquid and the thick suspension will be increasing with passage of time.
a) True
b) False

View Answer

Answer: b [Reason:] With respect to Sedimentation, the boundary between the thick suspension and solids will be increasing and that between the between the clear liquid and the thick suspension will be decreasing with passage of time.

4. In sedimentation, l – clear liquid zone, t- thick suspension zone, s- solid zone. Which of the following curve with height of the interface as the y-axis and the time as the x-axis represent the s-t interface?
food-engineering-questions-answers-unit-operations-sedimentation-centrifuge-1-q4
a) a
b) b
c) Neither of the mentioned
d) Both of the mentioned

View Answer

Answer: a [Reason:] The s-t interface increase with time and then slightly decreases.

5. In sedimentation, l – clear liquid zone, t- thick suspension zone, s- solid zone. With concentration of solids as the y-axis and the time as the x-axis, which curve does the following represent?
food-engineering-questions-answers-unit-operations-sedimentation-centrifuge-1-q5
a) l-t interface
b) t-s interface
c) t zone
d) None of the mentioned

View Answer

Answer: b [Reason:] The above curve shows the t-s interface. The concentration of solids increases and then becomes constant.

6. The experimental details of the batch sedimentation experiment are comprehended by plotting which of the following two?
a) Height of interface against time
b) Concentration of solids against time
c) Settling rate vs slurry concentration
d) All of the mentioned

View Answer

Answer: a [Reason:] Height of interface against time is plotted to comprehend the batch sedimentation experiment.

7. Statement 1: For calculating the minimum thickener area, the angle bisector method is used.
Statement 2: In the angle bisector method, the point obtained the curve and the corresponding time is the time when the solids enter the compression zone.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] For calculating the minimum thickener area, the angle bisector method is used. In the angle bisector method, the point obtained the curve and the corresponding time is the time when the solids enter the compression zone.

8. The compression zone in batch sedimentation is considered the overflow.
a) True
b) False

View Answer

Answer: b [Reason:] The compression zone in batch sedimentation is considered the underflow.

9. Dorr-Oliver thickener is also called a _____
a) Continuous thickener
b) Raker
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Dorr-Oliver thickener is a continuous thickener which is also called a raker because of its extremely slow stirrer.

10. Which of the following is an application of sedimentation in the food industry?
a) Effluent treatment plant
b) Settling of dust on fruits
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Both of the mentioned, desludging of waters in effluent treatment plant and settling of dust particles present on fruits are the applications of sedimentation.

Set 3

1. Which of the following is an advantage of size reduction?
a) Enhanced heat/mass transfer
b) Intimate contact with certain food items
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Increased surface area due to size reduction enhances heat/mass transfer. Small sized particles have a more intimate contact with certain food items.

2. Statement 1: Dispersion of one immiscible liquid into another also involves size reduction.
Statement 2: Leaching requires size reduction.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Dispersion of one immiscible liquid into another also involves size reduction so that they mix well. Leaching requires size reduction as it is desirable to access the interior parts of the particles which is enhanced by reducing the size of the particles.

3. Which of the following is NOT true with respect to size reduction?
a) Size reduction is an energy inefficient process as the energy required for grinding is very high
b) Some of the energy liberated in the formation of new small surfaces is the grinding energy required by food material per unit surface area to form new surface areas and the rest is generally just heat
c) The crushing efficiency is inversely proportional to the surface created
d) None of the mentioned

View Answer

Answer: c [Reason:] The crushing efficiency is directly proportional to the surface created

4. Which of the following is NOT a method used for size reduction?
a) Cutting
b) Impact
c) Burning
d) Shear

View Answer

Answer: c [Reason:] Burning is NOT a method used for size reduction.

5. Statement 1: Grinding laws are based on the energy required for creation of new surface area.
Statement 2: In general, all the laws are based on the principle that the energy required per unit area of the surface is directly proportional to size of the particle.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Grinding laws are based on the energy required for creation of new surface area. In general, all the laws are based on the principle that the energy required per unit area of the surface is directly proportional to size of the particle.

6. Statement 1: A hammer mill uses impact to break particles.
Statement 2: A chakki uses compression to break particles.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: a [Reason:] A chakki uses attrition to break particles.

7. Kick’s law is an intermediate between rittinger’s law and bond’s law.
a) True
b) False

View Answer

Answer: b [Reason:] Bond’s law is an intermediate between rittinger’s law and kick’s law.

8. A jaw crusher uses _____
a) Compression
b) Shear
c) Cutting
d) None of the mentioned

View Answer

Answer: a [Reason:] A jaw crusher uses Compression.

9. A ball mill uses _____
a) Impact
b) Attrition
c) Both of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] A ball mill uses both impact when the solids fall from the top to the bottom and attrition when the particles rub against each other and reduce in size.

10. Which of the following uses attrition?
a) Ball mill
b) Plate mill
c) Roller mill
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned use attrition for size reduction.

Set 4

1. Which of the following is NOT an application of mixing solids in the food industry?
a) Biscuit/bakery making
b) Poultry and cattle feed
c) Chips and snacks industry
d) None of the mentioned

View Answer

Answer: d [Reason:] All the mentioned are applications of mixing in the food industry.

2. Which of the following is NOT a mixing involved with fluids in the food industry?
a) Soup powders
b) Carbonated drinks
c) Oxygen transfer in fermentation broths
d) None of the mentioned

View Answer

Answer: a [Reason:] Soup powders involve mixing of solids. Carbonated drinks involve mixing of gas with liquid. Oxygen transfer in fermentation broths involves mixing of gas in liquid again.

3. Which of the following does NOT include power required for mixing by an impeller?
a) Rheological nature of the fluid
b) Friction in the motor
c) Speed, nature and type of the impeller
d) None of the mentioned

View Answer

Answer: b [Reason:] Friction in the motor does NOT include power required for mixing by an impeller.

4. Power required for a gassed system is more than that required for an ungassed system.
a) True
b) False

View Answer

Answer: b [Reason:] Power required for an ungassed system is more than that required for a gassed system. This is because when a gas is sent into the fluid via a nozzle, the density of the fluid near the impeller decreases and hence the power required for it is lesser.

5. Statement 1: Froude number relates the gravitational effect which is important when the liquid is agitated by an impeller.
Statement 2: When NRe,i < 300, NFr is ineffective.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Froude number relates the gravitational effect which is important when the liquid is agitated by an impeller. When NRe,i < 300, NFr is ineffective.

6. With respect to the relationship between the power number and the impeller Reynolds’s number, which amongst the following statements is true?
a) In the turbulent region, the NRe,i has no impact over NPo
b) In the transient region, the NRe,i has no impact over NPo
c) In the laminar region, the NPo continually falls as NRe,i increases
d) None of the mentioned

View Answer

Answer: a [Reason:] In the turbulent region, the NRe,i, impeller Reynolds’s number, has no impact over NPo, power number.

7. Statement 1: In the transient zone, the power input depends on the density and viscosity of the fluid.
Statement 2: In the laminar zone, the power input depends on the density only. It is independent of the viscosity of the fluid.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: a [Reason:] In the laminar zone, the power input depends on the viscosity only. It is independent of the density of the fluid.

8. Statement 1: For non-Newtonian fluids, another term called apparent viscosity is used as their viscosity changes with the change in the shear rate.
Statement 2: For non-Newtonian fluids, between the transition region, the power number for non-Newtonian fluids is slightly higher than that for Newtonian fluids.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: a [Reason:] For non-Newtonian fluids, between the transition region, the power number for non-Newtonian fluids is slightly lower than that for Newtonian fluids.

9. Statement 1: Where Pg is power for a gassed system and Po is power for an ungassed system, Pg/Po is _____
Statement 2: Na stands for _____
a) < 1, aeration number
b) > 1, aeration number
c) < 1, consistency index
d) > 1, consistency index

View Answer

Answer: a [Reason:] Power required for an ungassed system Po is more than that required for a gassed system Pg. This is because when a gas is sent into the fluid via a nozzle, the density of the fluid near the impeller decreases and hence the power required for it is lesser.

10. Statement 1: Flat blade/curve blade/arrow head/vaned disc turbines are generally used for gas-liquid mixing.
Statement 2: Helical screw/ribbon mixer/gate anchor are generally used for solid-solid mixing.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Flat blade/curve blade/arrow head/vaned disc turbines are generally used for gas-liquid mixing. Helical screw/ribbon mixer/gate anchor are generally used for solid-solid mixing.

11. Which of the following is true with respect to Carbonation?
a) Gas-liquid mixing
b) Helps improve storage life
c) Increased pressure
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned are true with respect to Carbonation.

12. With respect to dipping oil emulsions, which of the following is true?
a) Used for easy dehydration of food
b) Gives a thin layer of coating on the fruit berries
c) Dipping oil made from an emulsion by mixing of fatty esters with some amount of aqueous potassium carbonate solutions by high speed impellers
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned is true about dipping oil emulsions.

Set 5

1. There are ____ common types of bevel gears.
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: b [Reason:] Spiral and straight.

2. Straight bevel gears are easy to design and manufacture and give reasonably good service with quieter operation.
a) True
b) No, noise problem
c) No, vibration problem
d) None of the listed

View Answer

Answer: b [Reason:] They produce a lot of noise while working.

3. Which of the following creates smoother motion?
a) Straight bevel gears
b) Spiral bevel gears
c) Equal for straight and spiral
d) None of the mentioned

View Answer

Answer: b [Reason:] Spiral bevel gear has smooth engagement which results in quieter operation.

4. When the pitch angle is greater than 90⁰, it is called external bevel gear.
a) True
b) Internal
c) Helical
d) Herringbone

View Answer

Answer: b [Reason:] For external bevel gear, pitch angle is less than 90⁰.

5. For crown bevel gear, pitch angle is
a) <90
b) =90
c) >90
d) None of the listed

View Answer

Answer: b [Reason:] Crown gears are characterised by pitch angle of 90⁰.

6. If pitch angle is >90, the bevel gear is?
a) Internal
b) External
c) Crown
d) Static

View Answer

Answer: a [Reason:] Nomenclature.

7. Miter gears are the bevel gears mounted on shaft which are intersecting at angle greater than 90.
a) True
b) False

View Answer

Answer: b [Reason:] The shafts which are intersecting at 90.

8. Crown gears having a pitch angle of 90⁰ are mounted on shafts intersecting at an angle
a) =90
b) <90
c) >90
d) None of the listed

View Answer

Answer: c [Reason:] Application of crown gear according to its structure.

9. Which of the following are characteristics of skew bevel gears?
a) Straight teeth
b) Mounted on parallel shafts
c) Mounted on intersecting shafts
d) All of the mentioned

View Answer

Answer: a [Reason:] They are used in non-parallel and non-intersecting shafts.

10. Hypoid gears are based on surfaces that are paraboloids of revolution.
a) True
b) False

View Answer

Answer: b [Reason:] They are hyperboloids of revolution.

11. When two hyperboloids are rotated, the resulting motion is
a) Sliding
b) Turning
c) Combination of turning and sliding
d) Rotary

View Answer

Answer: c [Reason:] There is turning as well as sliding motion.

12. In hypoid bevel gears, shafts may continue past each other.
a) True
b) False

View Answer

Answer: a [Reason:] Offset of the shaft is quite considerable in case of hypoid gears.

13. Hypoid gears have the following characteristics.
a) Curved teeth
b) Mounted on non -parallel non intersecting shafts
c) Efficiency of 97%
d) All of the mentioned

View Answer

Answer: d [Reason:] It has curved teeth and are mounted on non-parallel non intersecting shafts with efficiency of 96-98%.

14. Zerol gears are straight bevel gears with zero spiral angle.
a) True
b) False

View Answer

Answer: b [Reason:] They happen to fall in the category of spiral bevel gears.

15. Zerol gears give lesser contact ratio.
a) True
b) No, larger contact ratio
c) Zero contact
d) None of the listed

View Answer

Answer: b [Reason:] Zerol gears have more gradual contact and slighter larger contact ratio.