# Dairy Engineering Questions and Answers – Flow Behaviour Models

This set of Dairy Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Flow Behaviour Models”.

1. At 30℃, water has the viscosity of __________
a) 0.801
b) 1
c) 2
d) 6.29

Explanation: Water has the viscosity of 0.801 at the temperature of 30℃. Water at 20.2oC (68.4oF) has the absolute viscosity of one – 1 – centipoises.

2. Viscosity of milk and milk products is important in not determining __________
a) the rate of creaming
b) rates of mass and heat transfer
c) the flow conditions in dairy processes
d) spoilage rate

Explanation: Viscosity of milk and milk products plays an important role in determining the rate of creaming. It also helps in determining rates of mass and heat transfer and flow conditions in the dairy process.

3. Skim milk exhibit which of the following flow behavior?
a) Newtonian
b) Non Newtonian
c) Pseudo plastic
d) Diliant

Explanation: Skim milk has Newtonian behavior. It shows stress and strain directly corresponding to each other.

4. Viscosity of Skim milk depends on __________
a) Temperature
b) pH
c) Temperature and pH
d) Moisture

Explanation: Viscosity of Skim milk is dependent on temperature. The pH of milk also plays a vital role in determining the viscosity of skim milk.

5. Decrease in temperature of milk leads to _______ in viscosity.
a) Parabolic decrease
b) Linear decrease
c) Constant
d) Increase

Explanation: Cooler temperatures increase viscosity. This can be due to the voluminosity of casein micelles.

6. Temperatures above 65° C _______ viscosity of skim milk.
a) Parabolic decrease
b) Linear decrease
c) Constant
d) Increase

Explanation: In skim milk, temperatures above 65° C increase viscosity. This is due to the denaturation of whey proteins.

7. Cooled raw milk and cream exhibit which of the following flow behavior?
a) Newtonian
b) Non Newtonian
c) Sticky
d) None

Explanation: Cooled raw milk and cream show non-Newtonian behavior in which the viscosity is dependent on the shear rate.

8. Which of the following factors does not affect the viscosity of milk?
a) State and concentration of proteins
b) State and concentration of Fat
c) Temperature and Age of Milk
d) Spoilage

Explanation: Important factors that influence the viscosity of milk are State and concentration of protein. State and concentration of fat; Temperature of milk and Age of the milk also influence viscosity.

9. The unit of viscosity is __________
a) Gamma
b) Pascal
c) Poise
d) Bar

Explanation: The unit of viscosity is poise. Bar is the unit of pressure. Pascal is also a unit of pressure.

10. Lactose, whey proteins and milk salts have less contribution towards the viscosity of milk compared with the casein which alone is contributing substantially towards this property.
a) True
b) False

Explanation: The statement is true. Lactose, whey proteins and milk salts contribute less towards the viscosity. Casein contributes substantially towards this property.

11. The force required to maintain a relative velocity of 1cm/sec between two parallel planes placed 1 cm apart is called ________
a) acceleration
b) buoyancy force
c) viscosity
d) flow

Explanation: The force required to maintain a relative velocity of 1cm/sec between two parallel planes placed 1 cm apart is called viscosity. It has a unit of poise.

12. Flow is a kind of __________
a) Breakage
b) Reversible deformation
c) Irreversible deformation
d) Liquid

Explanation: Flow is an irreversible deformation. Irreversible deformation can be defined as a state when a matter is not reverted to the original state when the force is removed.

13. Elasticity is___________
a) Breakage
b) Reversible deformation
c) Irreversible deformation
d) Liquid

Explanation: Elasticity is reversible deformation. Reversible deformation can be defined as a state when a matter is reverted to the original form after stress is removed.

14. Deformation force can be ______________
a) Static
b) Dynamic
c) Static and dynamic
d) Short

Explanation: The deformation forces which act on a solid body or a liquid can be Static: the force is acting constantly and its direction and magnitude are constant and dynamic: the magnitude and/or direction of the force(s) are variable as a function of time.

15. Viscosity varied ________ with temperature and _______ with fat content of milk.
a) Linearly and exponentially
b) Exponentially and linearly
c) Exponentially and exponentially
d) Linearly and linearly

Explanation: Viscosity varies exponentially with temperature and linearly with a fat content of milk. Viscosity for the fat and temperature range measured varied from 1-60 centipoises.

Sanfoundry Global Education & Learning Series – Dairy Engineering.

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