Important in the beginning of filtration

Decreased with the time of filtration

Is less realistic in estimating the power requirements of commercial crushers

Calls for relatively less energy for the smaller product particles, than does the Rittinger law

Is less realistic in estimating the power requirements of commercial crushers

States that the work required to form particle of any size from very large feed is proportional to the square root of the volume to surface ratio of the product

States that the work required for the crushing is proportional to the new surface created

A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ≈ì√ÖL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is ≈í¬• and no cake is formed. The initial pressure drop during filtration is%!

¬¨Œ©w¬¨‚â§ . R . ≈ì√ÖL(R + 2≈í¬•)

¬¨Œ©w¬¨‚â§ . R¬¨‚â§ . ≈ì√ÖL

¬¨Œ©w¬¨‚â§ . ≈í¬•¬¨‚â§ . ≈ì√ÖL

¬¨Œ©w¬¨‚â§ . ≈í¬•≈ì√ÖL (2R + ≈í¬•)

¬¨Œ©w¬¨‚â§ . R . ≈ì√ÖL(R + 2≈í¬•)

In the cyclone separator used for separation of dust from dust laden gas, the gas%!

Enters the cyclone from the top

Is admitted tangentially at high velocity

Develops a helical motion inside the chamber

A screen is said to be blinded, when the%!

Screen capacity is abruptly increased

Oversizes are present in undersize fraction

Undersizes are retained in oversize fraction

Screen is plugged with solid particles

Screen capacity is abruptly increased

__________ centrifuge is the most suitable for separation of non-friable crystals.

Perforated horizontal basket continuous

Not suitable, if the liquid is the main product

Having prohibitively high maintenance cost

Not suitable for wide range of materials under varying operating conditions of cake thickness and pressure

During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration%!

When half the filtrate has been obtained

At the end of filtration, but decreases with time subsequently

*$_Bucket elevators are not suitable for the vertical lifting of __________ materials.?

Small lumpy (e.g. grains and sand)

Fine (e.g. - 200 mesh size coal)

Small lumpy (e.g. grains and sand)

398 + Mcqs in Mechanical Operations in Chemical Engineering Page 1 McqOptions

1.	Helical screw agitator is used for%!
A.	Mixing highly viscous pastes
B.	Blending immiscible liquids
C.
Answer» B. Blending immiscible liquids

Discussion

2.	Cake resistance is%!
A.	Important in the beginning of filtration
B.	Decreased with the time of filtration
C.	Independent of pressure drop
D.	None of these
Answer» E.

Discussion

3.	Compressibility co-efficient for an absolutely compressible cake is%!
A.	0
B.	1
C.	0 to 1
D.	‚Äö√ √ª
Answer» C. 0 to 1

Discussion

4.	Bond crushing law%!
A.	Calls for relatively less energy for the smaller product particles, than does the Rittinger law
B.	Is less realistic in estimating the power requirements of commercial crushers
C.	States that the work required to form particle of any size from very large feed is proportional to the square root of the volume to surface ratio of the product
D.	States that the work required for the crushing is proportional to the new surface created
Answer» B. Is less realistic in estimating the power requirements of commercial crushers

Discussion

5.	Handling of ashes and similar materials can be done best by a __________ conveyor.%!
A.	Flight
B.	Drag or slat
C.	Belt
D.	Ribbon
Answer» C. Belt

Discussion

6.	Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation?%!
A.	Check plates
B.	Jaw plates
C.	Toggles
D.	Crush shaft
Answer» C. Toggles

Discussion

7.	The distribution given by microscopic analysis of powder is%!
A.	Number
B.	Length
C.	Area
D.	Volume
Answer» B. Length

Discussion

8.	In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the%!
A.	Square root of the velocity
B.	Square of the viscosity
C.	Filtration time only
D.	Washing time only
Answer» B. Square of the viscosity

Discussion

9.	The sphericity of a solid particle of cubical shape is%!
A.	≈ì√Ñ
B.	(≈ì√Ñ/6)1/3
C.	(≈ì√Ñ/6)1/2
D.	≈ì√Ñ/3
Answer» C. (≈ì√Ñ/6)1/2

Discussion

10.	Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is%!
A.	>10
B.	<10
C.	>100
D.	<100
Answer» C. >100

Discussion

11.	Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is%!
A.	0.5
B.	1
C.	‚Äö√ √∂2
D.	‚Äö√ √∂3
Answer» C. ‚Äö√ √∂2

Discussion

12.	The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area, m¬¨‚â§ V = rising velocity of fluid, m/sec.S = percentage of solids in the suspension by volume.≈ì√Ö = density of solids, kg/m¬¨‚â•)%!
A.	3.6 AVS.≈ì√Ö
B.	3.6 A.V.≈ì√Ö
C.	3.6 A.S. ≈ì√Ö
D.	3.6 AVS/≈ì√Ö
Answer» B. 3.6 A.V.≈ì√Ö

Discussion

13.	Dry powdery solid materials are transported by a __________ conveyor.%!
A.	Belt
B.	Bucket
C.	Screw
D.	None of these
Answer» D. None of these

Discussion

14.	A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ≈ì√ÖL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is ≈í¬• and no cake is formed. The initial pressure drop during filtration is%!
A.	¬¨Œ©w¬¨‚â§ . R¬¨‚â§ . ≈ì√ÖL
B.	¬¨Œ©w¬¨‚â§ . ≈í¬•¬¨‚â§ . ≈ì√ÖL
C.	¬¨Œ©w¬¨‚â§ . ≈í¬•≈ì√ÖL (2R + ≈í¬•)
D.	¬¨Œ©w¬¨‚â§ . R . ≈ì√ÖL(R + 2≈í¬•)
Answer» D. ¬¨Œ©w¬¨‚â§ . R . ≈ì√ÖL(R + 2≈í¬•)

Discussion

15.	In the cyclone separator used for separation of dust from dust laden gas, the gas%!
A.	Enters the cyclone from the top
B.	Is admitted tangentially at high velocity
C.	Develops a helical motion inside the chamber
D.	Both B and C
Answer» E.

Discussion

16.	Which of the following conveyors cannot be recommended for transportation of abrasive materials?%!
A.	Belt conveyor
B.	Apron conveyor
C.	Flight conveyor
D.	Chain conveyor
Answer» D. Chain conveyor

Discussion

17.	A screen is said to be blinded, when the%!
A.	Oversizes are present in undersize fraction
B.	Undersizes are retained in oversize fraction
C.	Screen is plugged with solid particles
D.	Screen capacity is abruptly increased
Answer» D. Screen capacity is abruptly increased

Discussion

18.	In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the __________ crushing.%!
A.	Secondary
B.	Fine
C.	Primary
D.	Ultrafine
Answer» D. Ultrafine

Discussion

19.	The study on washability of coal is done by using the __________ technique.%!
A.	Tabling
B.	Elutriation
C.	Heavy media separation
D.	None of these
Answer» D. None of these

Discussion

20.	__________ is the most commonly used 'filter aid'.%!
A.	Diatomaceous earth
B.	Fuller's earth
C.	Vermiculite
D.	Semi-plastic clay
Answer» B. Fuller's earth

Discussion

21.	In classification, particles are said to be equal settling, if they have the same terminal velocities in the%!
A.	Different fluids
B.	Same fluid
C.	Same field of force
D.	Both B and C
Answer» E.

Discussion

22.	Screen capacity is expressed in terms of%!
A.	Tons/hr
B.	Tons/ft¬¨‚â§
C.	Both A & B
D.	Tons/hr-ft¬¨‚â§
Answer» E.

Discussion

23.	Pine oil used in froth floatation technique acts as a/an%!
A.	Collector
B.	Modifier
C.	Frother
D.	Activator
Answer» D. Activator

Discussion

24.	Size reduction of moulding powders, waxes, resins & gums are done in a __________ mill.%!
A.	Cage
B.	Hammer
C.	Both A & B
D.	Neither A nor B
Answer» D. Neither A nor B

Discussion

25.	__________ centrifuge is the most suitable for separation of non-friable crystals.
A.	Tubular bowl
B.	Disc-bowl
C.	Perforated horizontal basket continuous
D.	Suspended batch basket
Answer» D. Suspended batch basket

Discussion

26.	increasing the capacity of a screen __________ the screen effectiveness.%!
A.	Decreases
B.	Increases
C.	Does not effect
D.	None of these
Answer» B. Increases

Discussion

27.	What is the critical rotation speed in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm dia balls?%!
A.	0.5
B.	1.0
C.	2.76
D.	0.66
Answer» E.

Discussion

28.	Wet seiving is employed, when the product contains __________ materials.%!
A.	Abrasive
B.	Large quantity of very fine
C.	Coarse
D.	Non-sticky
Answer» C. Coarse

Discussion

29.	Which of the following crushers can be considered as a combination of a jaw crusher and a roller crusher?%!
A.	Rod mill
B.	Fluid energy mill
C.	Gyratory crusher
D.	Ball mill
Answer» D. Ball mill

Discussion

30.	Basic slag is not ground in%!
A.	Jaw crushers
B.	Ball mills
C.	Compartment mills
D.	Tube mills
Answer» B. Ball mills

Discussion

31.	A filter press is%!
A.	A batch filter
B.	Not suitable, if the liquid is the main product
C.	Having prohibitively high maintenance cost
D.	Not suitable for wide range of materials under varying operating conditions of cake thickness and pressure
Answer» B. Not suitable, if the liquid is the main product

Discussion

32.	A widely used size reduction equipment for __________ is Bradford breaker.%!
A.	Talc
B.	Coal
C.	Iron core
D.	Wheat
Answer» C. Iron core

Discussion

33.	During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration%!
A.	At time zero
B.	At the end of filtration
C.	When half the filtrate has been obtained
D.	At the end of filtration, but decreases with time subsequently
Answer» C. When half the filtrate has been obtained

Discussion

34.	In a mixer, the quantity, (v. L/D) is termed as __________ number(where, v = longitudinal velocity of material, L = length of the mixer, D = diffusivity in axial mixing).%!
A.	Weber
B.	Peclet
C.	Brinkman
D.	Schmidt
Answer» C. Brinkman

Discussion

35.	Capacity (in tons/hr) of jaw/gyratory crusher is equal to (where, L = length of the receiving opening, cm S = greater width of the discharge opening, cm)%!
A.	0.01 L.S
B.	0.087 L.S
C.	L.S
D.	L.S/0.087
Answer» C. L.S

Discussion

36.	Which of the following is not a revolving/tumbling mill used for size reduction?%!
A.	Compartment mill
B.	Pebble mill
C.	Cage mill
D.	Rod mill
Answer» D. Rod mill

Discussion

37.	Shape factor for a cylinder whose length equals its diameter is%!
A.	1.5
B.	0.5
C.	1.0
D.	2.0
Answer» B. 0.5

Discussion

38.	__________ balls capable of grinding the feed in a ball mill gives the maximum efficiency.%!
A.	Cast iron
B.	Minimum size
C.	Maximum size
D.	Elliptical
Answer» C. Maximum size

Discussion

39.	Dust collection efficiency of electrostatic precipitator can be as high as 99.9%. Maximum temperature and pressure of dust laden gas that can be cleaned in an electrostatic precipitator is respectively.%!
A.	200¬¨‚àûC and 5 atm
B.	1000¬¨‚àûC and 10 atm
C.	500¬¨‚àûC and 50 atm
D.	1000¬¨‚àûC and 500 atm
Answer» C. 500¬¨‚àûC and 50 atm

Discussion

40.	Sauter mean diameter is the same as the __________ mean diameter.%!
A.	Mass
B.	Arithmetic
C.	Volume-surface
D.	Geometric
Answer» D. Geometric

Discussion

41.	200 mesh screen means 200 openings per%!
A.	Cm¬¨‚â§
B.	Cm
C.	Inch
D.	Inch¬¨‚â§
Answer» D. Inch¬¨‚â§

Discussion

42.	Cyclones are used primarily for separating%!
A.	Solids
B.	Solids from fluids
C.	Liquids
D.	Solids from solids
Answer» C. Liquids

Discussion

43.	Pine oil and cresylic acid are used as __________ in the froth floatation process.%!
A.	Frother
B.	Collector
C.	Depressor
D.	Conditioner
Answer» B. Collector

Discussion

44.	*$_200 mesh screen means 200 openings per?
A.	Cm¬¨‚â§
B.	Cm
C.	Inch
D.	Inch¬¨‚â§
Answer» D. Inch¬¨‚â§

Discussion

45.	*$_Sauter mean diameter is the same as the __________ mean diameter.?
A.	Mass
B.	Arithmetic
C.	Volume-surface
D.	Geometric
Answer» D. Geometric

Discussion

46.	*$_Pine oil and cresylic acid are used as __________ in the froth floatation process.?
A.	Frother
B.	Collector
C.	Depressor
D.	Conditioner
Answer» B. Collector

Discussion

47.	*$_Cyclones are used primarily for separating?
A.	Solids
B.	Solids from fluids
C.	Liquids
D.	Solids from solids
Answer» C. Liquids

Discussion

48.	*$_Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter)?
A.	0.5 D
B.	D
C.	1.5 D
D.	2 D
Answer» C. 1.5 D

Discussion

49.	*$_Bucket elevators are not suitable for the vertical lifting of __________ materials.?
A.	Fine (e.g. - 200 mesh size coal)
B.	Sticky (e.g. clay paste)
C.	Small lumpy (e.g. grains and sand)
D.	Free flowing
Answer» C. Small lumpy (e.g. grains and sand)

Discussion

50.	*$_Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with __________ to get the same for dry grinding.?
A.	1.0
B.	0.5
C.	1.34
D.	4.34
Answer» D. 4.34

Discussion

Explore topic-wise MCQs in Chemical Engineering.

Helical screw agitator is used for%!

Cake resistance is%!

Compressibility co-efficient for an absolutely compressible cake is%!

Bond crushing law%!

Handling of ashes and similar materials can be done best by a __________ conveyor.%!

Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation?%!

The distribution given by microscopic analysis of powder is%!

In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the%!

The sphericity of a solid particle of cubical shape is%!

Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is%!

Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is%!

The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area, m¬¨‚â§ V = rising velocity of fluid, m/sec.S = percentage of solids in the suspension by volume.≈ì√Ö = density of solids, kg/m¬¨‚â•)%!

Dry powdery solid materials are transported by a __________ conveyor.%!

A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ≈ì√ÖL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is ≈í¬• and no cake is formed. The initial pressure drop during filtration is%!

In the cyclone separator used for separation of dust from dust laden gas, the gas%!

Which of the following conveyors cannot be recommended for transportation of abrasive materials?%!

A screen is said to be blinded, when the%!

In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the __________ crushing.%!

The study on washability of coal is done by using the __________ technique.%!

__________ is the most commonly used 'filter aid'.%!

In classification, particles are said to be equal settling, if they have the same terminal velocities in the%!

Screen capacity is expressed in terms of%!

Pine oil used in froth floatation technique acts as a/an%!

Size reduction of moulding powders, waxes, resins & gums are done in a __________ mill.%!

__________ centrifuge is the most suitable for separation of non-friable crystals.

increasing the capacity of a screen __________ the screen effectiveness.%!

What is the critical rotation speed in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm dia balls?%!

Wet seiving is employed, when the product contains __________ materials.%!

Which of the following crushers can be considered as a combination of a jaw crusher and a roller crusher?%!

Basic slag is not ground in%!

A filter press is%!

A widely used size reduction equipment for __________ is Bradford breaker.%!

During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration%!

In a mixer, the quantity, (v. L/D) is termed as __________ number(where, v = longitudinal velocity of material, L = length of the mixer, D = diffusivity in axial mixing).%!

Capacity (in tons/hr) of jaw/gyratory crusher is equal to (where, L = length of the receiving opening, cm S = greater width of the discharge opening, cm)%!

Which of the following is not a revolving/tumbling mill used for size reduction?%!

Shape factor for a cylinder whose length equals its diameter is%!

__________ balls capable of grinding the feed in a ball mill gives the maximum efficiency.%!

Dust collection efficiency of electrostatic precipitator can be as high as 99.9%. Maximum temperature and pressure of dust laden gas that can be cleaned in an electrostatic precipitator is respectively.%!

Sauter mean diameter is the same as the __________ mean diameter.%!

200 mesh screen means 200 openings per%!

Cyclones are used primarily for separating%!

Pine oil and cresylic acid are used as __________ in the froth floatation process.%!

*$_200 mesh screen means 200 openings per?

*$_Sauter mean diameter is the same as the __________ mean diameter.?

*$_Pine oil and cresylic acid are used as __________ in the froth floatation process.?

*$_Cyclones are used primarily for separating?

*$_Bucket elevators are not suitable for the vertical lifting of __________ materials.?

*$_Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with __________ to get the same for dry grinding.?