Pick out the correct statement. (A) Bound moisture is removed during constant rate drying period (B) Free moisture is removed during falling rate drying period (C) The sum of free moisture and equilibrium moisture in a solid is called the critical moisture (D) The driving force for mass transfer in a wet solid is its free moisture content

Pick out the correct statement.

(A) Bound moisture is removed during constant rate drying period

(B) Free moisture is removed during falling rate drying period

(C) The sum of free moisture and equilibrium moisture in a solid is called the

critical moisture

(D) The driving force for mass transfer in a wet solid is its free moisture

content

by

1 Answer

Answer :

(D) The driving force for mass transfer in a wet solid is its free moisture

content

by

Related questions

Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to Nusselt number in heat transfer and Schmidt number to Prandtl number (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger (D) Hot gases at moderate pressure are usually in the shell side of shell and tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side

Description : Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to ... tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side

Last Answer : (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger

It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The equilibrium moisture content of the solid is 5%). (A) 15 min (B) 51 min (C) 71 min (D) 94 min

Description : It takes 6 hours to dry a wet solid from 50% moisture content to the critical moisture content of 15%. How much longer it will take to dry the solid to 10% moisture content, under the same drying conditions? (The ... 5%). (A) 15 min (B) 51 min (C) 71 min (D) 94 min

Last Answer : (C) 71 min

The critical moisture content in case of drying indicates the __________ rate period. (A) Beginning of falling (B) Beginning of constant (C) End of falling (D) None of these

Description : The critical moisture content in case of drying indicates the __________ rate period. (A) Beginning of falling (B) Beginning of constant (C) End of falling (D) None of these

Last Answer : (A) Beginning of falling

The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 2 (D) T

Description : The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 2 (D) T

Last Answer : (C) T

During drying operation, it is easier to remove the __________ moisture. (A) Equilibrium (B) Critical (C) Unbound (D) Bound

Description : During drying operation, it is easier to remove the __________ moisture. (A) Equilibrium (B) Critical (C) Unbound (D) Bound

Last Answer : (C) Unbound

Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the __________ moisture. (A) Unbound (B) Critical (C) Free (D) Bound

Description : Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the __________ moisture. (A) Unbound (B) Critical (C) Free (D) Bound

Last Answer : (A) Unbound

During drying of a solid, the critical moisture content increases with (A) Decreased drying rate (B) Increased thickness of the solid (C) Increased drying rate (D) Both (B) and (C)

Description : During drying of a solid, the critical moisture content increases with (A) Decreased drying rate (B) Increased thickness of the solid (C) Increased drying rate (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

During the constant rate period of drying of a solid, (A) Increased air humidity decreases the rate of drying (B) Increasing the air temperature decreases the drying rate (C) Surface evaporation of unbound moisture occurs (D) None of these

Description : During the constant rate period of drying of a solid, (A) Increased air humidity decreases the rate of drying (B) Increasing the air temperature decreases the drying rate (C) Surface evaporation of unbound moisture occurs (D) None of these

Last Answer : (C) Surface evaporation of unbound moisture occurs

The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 1.5 (D) T

Description : The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 1.5 (D) T

Last Answer : (B) T

In the constant rate period of the rate of drying curve for batch drying, (A) Cracks develop on the surface of the solid (B) Rate of drying decreases abruptly (C) Surface evaporation of unbound moisture occurs (D) None of these

Description : In the constant rate period of the rate of drying curve for batch drying, (A) Cracks develop on the surface of the solid (B) Rate of drying decreases abruptly (C) Surface evaporation of unbound moisture occurs (D) None of these

Last Answer : (C) Surface evaporation of unbound moisture occurs

Moisture contained by a substance in excess of the equilibrium moisture is called the __________ moisture. (A) Unbound (B) Free (C) Critical (D) Bound

Description : Moisture contained by a substance in excess of the equilibrium moisture is called the __________ moisture. (A) Unbound (B) Free (C) Critical (D) Bound

Last Answer : (B) Free

Pick out the wrong statement. (A) Different solids have different equilibrium moisture curves (B) Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele method of theoretical plate calculation for distillation column (C) Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column (D) Even a forced draft cooling tower cannot cool water below the wet bulb temperature

Description : Pick out the wrong statement. (A) Different solids have different equilibrium moisture curves (B) Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele method of ... (D) Even a forced draft cooling tower cannot cool water below the wet bulb temperature

Last Answer : (C) Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column

Pick out the wrong statement: (A) Change in barometric pressure does not affect the relative humidity (B) In case of a packed tower, the operating velocity is about half of the flooding velocity, generally (C) 'Elution' means the desorption of the adsorbed solute by a solvent (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity

Description : Pick out the wrong statement: (A) Change in barometric pressure does not affect the relative humidity (B) In case of a packed tower, the operating velocity is about half of the ... (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity

Last Answer : (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity

Moisture content of a substance when at equilibrium with a given partial pressure of the vapour is called the __________ moisture. (A) Free (B) Unbound (C) Equilibrium (D) Bound

Description : Moisture content of a substance when at equilibrium with a given partial pressure of the vapour is called the __________ moisture. (A) Free (B) Unbound (C) Equilibrium (D) Bound

Last Answer : (C) Equilibrium

With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________, if the conduction and radiation through the solid are negligible. (A) Increases (B) Decreases (C) Remain same

Description : With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________, if the conduction and radiation through the solid are negligible. (A) Increases (B) Decreases (C) Remain same

Last Answer : (A) Increases

Drying operation under vacuum is carried out to (A) Dry those materials which have very high unbound moisture content (B) Reduce drying temperature (C) Increase drying temperature (D) Dry materials having high bound moisture content

Description : Drying operation under vacuum is carried out to (A) Dry those materials which have very high unbound moisture content (B) Reduce drying temperature (C) Increase drying temperature (D) Dry materials having high bound moisture content

Last Answer : (B) Reduce drying temperature

Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture. (A) Bound (B) Unbound (C) Critical (D) None of these

Description : Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture. (A) Bound (B) Unbound (C) Critical (D) None of these

Last Answer : (A) Bound

n a chemical factory where dyes are made, wet cake at 30 OC consisting of 60% moisture is put in a dryer to obtain an output having only 5% moisture, at atmospheric pressure. In each batch about 120 kgs of material is dried. a. The quantity of moisture removed per batch. b. What is the total quantity ( sensible & latent) of heat required to evaporate the moisture, if the latent heat of water is 540 kcal/kg at atmospheric conditions, Ignore heat absorbed by the solids c. Find the quantity of steam required for the drying process (per batch), if steam at 4 kg/cm2 is used for generating hot air in the dryer and the dryer efficiency is 80%. Latent heat of steam at 4 kg/cm2 is 520 kcal/kg.

Description : n a chemical factory where dyes are made, wet cake at 30 OC consisting of 60% moisture  is put in a dryer to obtain an output having only 5% moisture, at atmospheric pressure. In  each batch about 120 ... dryer and the dryer efficiency  is 80%. Latent heat of steam at 4 kg/cm2 is 520 kcal/kg.

Last Answer : Given that   Qty of material dried per batch - 120 Kgs  Moisture at inlet - 60% a. The quantity of moisture removed per batch.  Water quantity in a wet batch - 120 x 0.6 = 72 Kgs.  Quantity of bone dry ... - 48/0.95 = 50.5 Kgs.  Equivalent water in a dry batch - 50.5 - 48 = 2.5 Kgs.

Bound moisture is that liquid which exerts an equilibrium vapor pressure __________ that of the pure liquid at the given temperature. (A) Less than (B) More than (C) Equal to (D) Either (A) or (B); depends on the solid

Description : Bound moisture is that liquid which exerts an equilibrium vapor pressure __________ that of the pure liquid at the given temperature. (A) Less than (B) More than (C) Equal to (D) Either (A) or (B); depends on the solid

Last Answer : (A) Less than

The falling rate period in the drying of a solid is characterised by (A) Increase in rate of drying (B) Increasing temperatures both on the surface and within the solid (C) Decreasing temperatures (D) None of these

Description : The falling rate period in the drying of a solid is characterised by (A) Increase in rate of drying (B) Increasing temperatures both on the surface and within the solid (C) Decreasing temperatures (D) None of these

Last Answer : (B) Increasing temperatures both on the surface and within the solid

Pick out the correct statement about the condensation. (A) Filmwise condensation gives a lower heat transfer rate than the dropwise condensation (B) Suitable coating or vapour additive is used to promote film wise condensation (C) If a condensing liquid does not wet the surface dropwise, even then condensation will take place on it (D) Reynolds number of condensing liquid is based on its mass flow rate

Description : Pick out the correct statement about the condensation. (A) Filmwise condensation gives a lower heat transfer rate than the dropwise condensation (B) Suitable coating or vapour additive is used to promote film ... place on it (D) Reynolds number of condensing liquid is based on its mass flow rate

Last Answer : (B) Suitable coating or vapour additive is used to promote film wise condensation

Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate. (A) Increases (B) Decreases (C) Does not affect

Description : Occurrence of 'case hardening' during drying of a high moisture solid cake __________ the drying rate. (A) Increases (B) Decreases (C) Does not affect

Last Answer : (B) Decreases

Pick up the correct statement from the following: (A) O.M.C. refers to the moisture corresponding to the maximum point on the moisture content dry density curve (B) The line which shows moisture content dry density relation for soil containing a constant percentage of air voids, is known as air void line (C) The free fall of hammer for compaction is 30.5 cm (D) All the above

Description : Pick up the correct statement from the following: (A) O.M.C. refers to the moisture corresponding to the maximum point on the moisture content dry density curve (B) The line which shows moisture content dry ... void line (C) The free fall of hammer for compaction is 30.5 cm (D) All the above

Last Answer : (D) All the above

All moisture in a non-hygroscopic material is the __________ moisture. (A) Free (B) Equilibrium (C) Unbound (D) Bound

Description : All moisture in a non-hygroscopic material is the __________ moisture. (A) Free (B) Equilibrium (C) Unbound (D) Bound

Last Answer : (C) Unbound

Pick out the wrong statement. (A) Critical moisture content is not a property of the material itself (B) A sharp increase in pressure drop gives an indication of the flooding in a distillation column (C) Separation of components is not possible in liquid extraction, if selectivity is unity (D) Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum

Description : Pick out the wrong statement. (A) Critical moisture content is not a property of the material itself (B) A sharp increase in pressure drop gives an indication of the flooding in a ... unity (D) Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum

Last Answer : (D) Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum

Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant (A) Humidity (B) Velocity (C) Temperature (D) All (A), (B) & (C)

Description : Drying of a wet solid under constant drying conditions means the exposure of the wet solid to the air of constant (A) Humidity (B) Velocity (C) Temperature (D) All (A), (B) & (C)

Last Answer : (D) All (A), (B) & (C)

1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is (A) 520 (B) 200(C) 400 (D) 500

Description : 1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is (A) 520 (B) 200 (C) 400 (D) 500

Last Answer : (C) 400

If moisture content of solid on dry basis is X, then the same on wet basis is (A) X/(X + 1) (B) X/(1 - X) (C) (1 + X)/X (D) (1 - X)/X

Description : If moisture content of solid on dry basis is X, then the same on wet basis is (A) X/(X + 1) (B) X/(1 - X) (C) (1 + X)/X (D) (1 - X)/X

Last Answer : (A) X/(X + 1)

Pick out the correct statement. (A) A chemical reaction accompanied by absorption of heat is called an exothermic reaction (B) A chemical reaction accompanied by evolution of heat is called an endothermic reaction (C) The rate constant for a first order reaction does not change on changing the concentration units (D) Chemical equilibrium state is dynamic in nature

Description : Pick out the correct statement. (A) A chemical reaction accompanied by absorption of heat is called an exothermic reaction (B) A chemical reaction accompanied by evolution of heat is called an ... does not change on changing the concentration units (D) Chemical equilibrium state is dynamic in nature

Last Answer : (C) The rate constant for a first order reaction does not change on changing the concentration units

Pick out the correct statement. (A) A fat is converted into oil by its hydrogenation (B) There is no difference between a fat and an oil so far as its physical properties are concerned (C) All vegetable oils except coconut oil, contains fatty acids having more than sixteen carbon atoms (D) Vegetable oils are classified as drying, non-drying and semi drying oils depending upon their fatty acids content

Description : Pick out the correct statement. (A) A fat is converted into oil by its hydrogenation (B) There is no difference between a fat and an oil so far as its physical properties are ... Vegetable oils are classified as drying, non-drying and semi drying oils depending upon their fatty acids content

Last Answer : (C) All vegetable oils except coconut oil, contains fatty acids having more than sixteen carbon atoms

Drying of a solid involves __________ transfer. (A) Only heat (B) Only mass (C) Both heat and mass (D) None of these

Description : Drying of a solid involves __________ transfer. (A) Only heat (B) Only mass (C) Both heat and mass (D) None of these

Last Answer : (C) Both heat and mass

Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low interfacial tension (C) When Henry's law constant is very small, then the mass transfer rate is controlled by the gas film resistance (D) Taylor-Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers

Description : Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low ... Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers

Last Answer : (A) Mechanical agitation is required, if the system has low interfacial tension

Pick out the wrong statement pertaining to solvent extraction of oil. Rate of extraction (A) Decreases with decrease of thickness of the flakes(B) Increases with the increasing flake size keeping the flake thicknessconstant(C) Increases considerably with the rise of temperature(D) Decreases as the moisture content of flakes increases

Description : Pick out the wrong statement pertaining to solvent extraction of oil. Rate of extraction (A) Decreases with decrease of thickness of the flakes (B) Increases with the increasing flake size ... considerably with the rise of temperature (D) Decreases as the moisture content of flakes increases

Last Answer : (D) Decreases as the moisture content of flakes increases

Equilibrium moisture of a solid is equal to the total moisture minus free moisture. Which of the following substances will have maxi-mum equilibrium moisture? (A) Anthracite coal (B) Rag paper (C) Bamboo (D) Inorganic solids

Description : Equilibrium moisture of a solid is equal to the total moisture minus free moisture. Which of the following substances will have maxi-mum equilibrium moisture? (A) Anthracite coal (B) Rag paper (C) Bamboo (D) Inorganic solids

Last Answer : (C) Bamboo

During constant rate period, the rate of drying decreases with the (A) Decrease in air temperature (B) Increase in air humidity (C) Both (A) and (B) (D) Neither (A) nor (B)

Description : During constant rate period, the rate of drying decreases with the (A) Decrease in air temperature (B) Increase in air humidity (C) Both (A) and (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) and (B)

Pick out the correct statement. (A) Oxygen content decreases from lignite to bituminous coal as the coalification increases (B) The less the oxygen content, better is the coal, as it reduces the calorific value (C) With increase in oxygen content, moisture holding capacity of coal increases and the caking power decreases (D) All (A), (B) and (C)

Description : Pick out the correct statement. (A) Oxygen content decreases from lignite to bituminous coal as the coalification increases (B) The less the oxygen content, better is the coal, as it reduces the calorific value (C ... capacity of coal increases and the caking power decreases (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Advantage of continuous drying over batch drying is that the (A) Drying cost per unit weight of dried product is less (B) Product with more uniform moisture content is produced (C) Equipment size required is smaller (D) All 'a', 'b' & 'c'

Description : Advantage of continuous drying over batch drying is that the (A) Drying cost per unit weight of dried product is less (B) Product with more uniform moisture content is produced (C) Equipment size required is smaller (D) All 'a', 'b' & 'c'

Last Answer : (D) All 'a', 'b' & 'c'

For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same. (A) Unsaturated surface (B) Constant rate (C) Both (A) and (B) (D) Neither (A) nor (B)

Description : For __________ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same. (A) Unsaturated surface (B) Constant rate (C) Both (A) and (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) and (B)

A first order gaseous phase reaction is catalysed by a non-porous solid. The kinetic rate constant and the external mass transfer co-efficients are k and kg respectively. The effective rate constant (ke ff) is given by (A) ke ff = k + kg (B) ke ff = (k+ kg )/2 (C) ke ff = (kkg ) 1/2 (D) 1/ke ff = 1/k + 1/kg

Description : A first order gaseous phase reaction is catalysed by a non-porous solid. The kinetic rate constant and the external mass transfer co-efficients are k and kg respectively. The effective rate constant (ke ff) is given by (A) ke ff = k + kg ( ... + kg )/2 (C) ke ff = (kkg ) 1/2 (D) 1/ke ff = 1/k + 1/kg

Last Answer : (D) 1/ke ff = 1/k + 1/kg

Pick out the wrong statement. (A) Momentum transfer in laminar flow results from velocity gradient (B) A fluid in equilibrium is not free from shear stress (C) The viscosity of a non-Newtonian fluid is a function of temperature only (D) Both (B) and (C)

Description : Pick out the wrong statement. (A) Momentum transfer in laminar flow results from velocity gradient (B) A fluid in equilibrium is not free from shear stress (C) The viscosity of a non-Newtonian fluid is a function of temperature only (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

Pick up the correct statement from the following: (A) The dry density reduces by addition of water after attaining optimum moisture content (B) The line joining the peak of three moisture content graphs obtained by using three compactive energies, is called line of optimus (C) Well graded coarse grained soils can be compacted to a very high density as compared to fine grained soils (D) All the above

Description : Pick up the correct statement from the following: (A) The dry density reduces by addition of water after attaining optimum moisture content (B) The line joining the peak of three moisture content graphs ... be compacted to a very high density as compared to fine grained soils (D) All the above

Last Answer : Answer: Option D

Pick up the correct statement from the following: (A) The portion of pellicular water which remains unutilised, is called hygroscopic water (B) The moisture content at which permanent wilting of plants takes place, is called the wilting point (C) The moisture deficiency will be different at different points (D) All the above

Description : Pick up the correct statement from the following: (A) The portion of pellicular water which remains unutilised, is called hygroscopic water (B) The moisture content at which permanent wilting of plants ... point (C) The moisture deficiency will be different at different points (D) All the above

Last Answer : Answer: Option D

Pick up the correct statement from the following: (A) For thin structures subjected to wetting and drying, the water cement ratio should be 0.45 (B) For mass concrete structures subjected to wetting and drying, the water ratio should be 0.55 (C) For thin structures which remain continuously under water, the water-cement ratio by weight should be 0.55 (D) All the above

Description : Pick up the correct statement from the following: (A) For thin structures subjected to wetting and drying, the water cement ratio should be 0.45 (B) For mass concrete structures subjected to wetting and ... under water, the water-cement ratio by weight should be 0.55 (D) All the above

Last Answer : Answer: Option D

Pick up the incorrect statement from the following: (A) Compaction has no effect on the structure of a soil (B) Permeability decreases with increase in the dry density of a compacted soil (C) A wet side compacted soil is more compressible than a dry side compacted soil (D) Dry side compaction soils swell more when given access to moisture

Description : Pick up the incorrect statement from the following: (A) Compaction has no effect on the structure of a soil (B) Permeability decreases with increase in the dry density of a compacted soil (C) ... a dry side compacted soil (D) Dry side compaction soils swell more when given access to moisture

Last Answer : (A) Compaction has no effect on the structure of a soil

The vapour pressure exerted by the moisture contained in a wet solid depends upon the (A) Nature of the moisture (B) Temperature (C) Nature of the solid (D) All (A), (B) and (C)

Description : The vapour pressure exerted by the moisture contained in a wet solid depends upon the (A) Nature of the moisture (B) Temperature (C) Nature of the solid (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

To remove all the moisture from a wet solid it requires exposure to __________ air. (A) Perfectly dry (B) Highly humid (C) High temperature (D) None of these

Description : To remove all the moisture from a wet solid it requires exposure to __________ air. (A) Perfectly dry (B) Highly humid (C) High temperature (D) None of these

Last Answer : (A) Perfectly dry