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1. What does the following represents?
mechanical-operations-questions-answers-online-quiz-q1
a) Fourier’s law
b) Kick’s law
c) Newton’s law
d) Radiation law

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Answer: b [Reason:] Where, the rate of transport of mass, dm/dt across an interface of area A is proportional to the concentration gradient, dc/dx, across the interface.

2. As the particle size increases, flow properties also ___
a) Increase
b) Decrease
c) Remain same
d) Constant

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Answer: a [Reason:] As the particle size increases, flow properties also increases due to the influence of gravitational force on the size.

3. In a ______ the material present in the containers is agitated either by an oscillatory motion.
a) Propeller mixer
b) Shaker mixer
c) Impellor mixer
d) Turbine mixer

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Answer: b [Reason:] In these mixers, the material present in the containers is agitated either by an oscillatory for small scale mixing or by a rotary movement large scale mixing.

4. _____ may be used for mixing relatively low viscosity dispersions.
a) Propeller mixer
b) Shaker mixer
c) Impellor mixer
d) Motor mixer

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Answer: a [Reason:] They are comprising a rotating shaft with propeller blades attached, used for mixing relatively low viscosity dispersions (thicker solutions) and maintaining contents in suspension.

5. At what speed does the propeller mixer rotates?
a) 8000 rpm
b) 7000 rpm
c) 5000 rpm
d) 1000 rpm

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Answer: a [Reason:] It rotates at a very high speed i.e. up to 8000 r.p.m. due to which mixing is done in a short time, they are much smaller in diameter than paddle and turbine mixers.

6. What viscosity propellers can handle?
a) 2.0 pa.s
b) 1.5 pa.s
c) 5 pa.s
d) 8 pa.s

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Answer: a [Reason:] Propellers are used when high mixing capacity is needed. These are effective in handling liquids having a viscosity of about 2.0 Pascal second.

7. What are the power requirements of a radial impellor?
a) 50 to 100 hp
b) 1 to 1000 hp
c) 2 to 500 hp
d) 500 to 2000 hp

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Answer: b [Reason:] Power may range from 1 to 1000 hp, the impellor speed is typically between 50 and 150 rpm but it may be as high as 400 rpm.

8. The tank diameter to liquid ratio usually is ____
a) 1:1
b) 1:2
c) 2:3
d) 3:4

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Answer: a [Reason:] Equipment’s such as shaker mixers, propeller mixers, these equipment’s contain a flat bottomed with tank diameter to liquid ratio usually as 1:1.

9. For an impellor, Shearing action is very good at high speed.
a) True
b) False

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Answer: a [Reason:] It circulates by axial parallel flow to the shaft and its flow pattern is modified by the baffles, which also can cause shearing action at high speeds.

10. What power requirement’s does an axial impellor requires?
a) = 5 hp
b) > 2 hp
c) < 5 hp
d) > 5 hp

View Answer

Answer: d [Reason:] When a high axial circulation rate is desired, the power consumption is more than 5 horse power.

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