Food Engineering Multiple Choice Questions on ” Unit Operations – Mixing-1″.
1. Which of the following with respect to mixing is true?
a) It is used to distribute heat uniformly to all the components of the mixture
b) Mixing becomes difficult when one of the phases to be mixed is in minor quantity
c) Solid-solid mixing is more difficult than other phases
d) All of the mentioned
Answer: d
Clarification: All of the mentioned sentences are true with respect to mixing.
2. Statement 1: Root mean square is denoted by σ2
Statement 2: σ2 will show the variation of a composition obtained after mixing. Hence the lesser it is, the more efficient is the mixing.
a) True, False
b) True, True
c) False, False
d) False, True
Answer: b
Clarification: Root mean square is denoted by σ2. σ2 will show the variation of a composition obtained after mixing. Hence the lesser it is, the more efficient is the mixing.
3. Mixing index is applicable for mixing of solids at zero time.
a) True
b) False
Answer: a
Clarification: Mixing index is applicable for mixing of solids at zero time.
4. Which of the following conditions show that a certain industrial mixer is the best?
a) Power load for mixing is minimum
b) Standard deviation is minimum
c) Time required for mixing is minimum
d) All of the mentioned
Answer: d
Clarification: All of the mentioned conditions show that a certain industrial mixer is the best.
5. Mixing Index is a ratio of the standard deviation of various products during mixing to that at zero mixing.
a) True
b) False
Answer: a
Clarification: Mixing Index is a ratio of the standard deviation of various products during mixing to that at zero mixing.
6. Rate of mixing at any time is given by the extent of mixing at that particular time.
a) True
b) False
Answer: a
Clarification: Rate of mixing at any time is given by the extent of mixing at that particular time.
7. The force used for mixing by mixing equipment for pastes and dough is _____
a) Centrifugal smearing
b) Impact
c) Tumbling
d) All of the mentioned
Answer: d
Clarification: The force used for mixing by mixing equipment for pastes and dough can be any of the mentioned.
8. The clearance between the impeller and the vessel in a mixer is usually kept _____
a) High
b) Low
c) Cannot be determined
d) None of the mentioned
Answer: b
Clarification: The clearance between the impeller and the vessel is usually kept low to avoid stagnant zones.
9. Statement 1: Kneaders are specially used for pastry/viscous liquids in the food industry.
Statement 2: Kneaders are used for mixing dough with fats and making them homogeneous mixtures.
a) True, False
b) True, True
c) False, False
d) False, True
Answer: b
Clarification: Kneaders are specially used for pastry/viscous liquids in the food industry. Kneaders are used for mixing dough with fats and making them homogeneous mixtures.
10. Statement 1: Effectiveness of mixing in kneaders depends on the blade design.
Statement 2: Kneaders have a high clearance between the two oppositely rotating blades and the vessel.
a) True, False
b) True, True
c) False, False
d) False, True