Which of the following is not a chemical step in a fluid solid catalytic reaction? (A) Surface chemical reaction (B) Adsorption (C) Desorption (D) None of these

Which of the following is not a chemical step in a fluid solid catalytic
reaction?
(A) Surface chemical reaction
(B) Adsorption
(C) Desorption
(D) None of these
by

1 Answer

Answer :

(D) None of these
by

Related questions

For a heterogeneous catalytic reaction, A + B → C, with equimole feed of A and B, the initial rate - rA0 is invariant with total pressure. The rate controlling step is (A) Surface Kc /(1 + TS ) reaction between absorbed A and B in the gas phase (B) Surface reaction between absorbed A and absorbed B (C) Surface reaction between A in the gas phase and absorbed B(D) Desorption of C

Description : For a heterogeneous catalytic reaction, A + B → C, with equimole feed of A and B, the initial rate - rA0 is invariant with total pressure. The rate controlling step is (A) Surface Kc /(1 + TS ) ... A and absorbed B (C) Surface reaction between A in the gas phase and absorbed B (D) Desorption of C

Last Answer : (D) Desorption of C

__________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction. (A) Gas film diffusion (B) Ash diffusion (C) Chemical reaction (D) None of these

Description : __________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction. (A) Gas film diffusion (B) Ash diffusion (C) Chemical reaction (D) None of these

Last Answer : (C) Chemical reaction

Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature? (A) Pore diffusion (B) Film diffusion (C) Ash layer diffusion (D) Chemical reaction

Description : Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature? (A) Pore diffusion (B) Film diffusion (C) Ash layer diffusion (D) Chemical reaction

Last Answer : (B) Film diffusion

Overall rate of reaction in a heterogeneous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually __________ the concentration of catalyst, if it doesnot entail a chain mechanism.(A) Proportional to(B) Independent of(C) Inversely proportional to(D) Proportional to the square o

Description : Overall rate of reaction in a heterogeneous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually __________ the concentration of ... to (B) Independent of (C) Inversely proportional to (D) Proportional to the square o

Last Answer : (A) Proportional to

The rate expression for a heterogeneous catalytic reaction is given by, - rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR >> (1 + KA PA), the apparent activation energy EA is equal to (given E is the activation energy for the reaction and ΔHR and ΔHA are the activation energies of adsorption of R and A) (A) E (B) E + ΔHA (C) E + ΔHA - ΔHR ) (D) ΔHA + ΔHR

Description : The rate expression for a heterogeneous catalytic reaction is given by, - rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR ... R and A) (A) E (B) E + ΔHA (C) E + ΔHA - ΔHR ) (D) ΔHA + ΔHR

Last Answer : (C) E + ΔHA - ΔHR )

When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption. (A) Always lower than (B) Always higher than (C) Same as (D) Dependent on the system; can be either lower or higher than

Description : When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption. (A) Always lower than (B) Always higher than (C) Same as (D) Dependent on the system; can be either lower or higher than

Last Answer : (A) Always lower than

Though, theoretically the adsorption & desorption isotherms is expected to coincide but sometimes at least a part of the isotherms does not coincide and this phenomenon is known as adsorption hysteresis. In such cases, the desorption equilibrium pressure is __________ that obtained for adsorption. (A) Lower than (B) Higher than (C) Same as (D) Either same or higher than

Description : Though, theoretically the adsorption & desorption isotherms is expected to coincide but sometimes at least a part of the isotherms does not coincide and this phenomenon is known as adsorption hysteresis. In such ... (B) Higher than (C) Same as (D) Either same or higher than

Last Answer : (A) Lower than

There is desorption of physical adsorption when

Description : There is desorption of physical adsorption when

Last Answer : There is desorption of physical adsorption when A. temperature is increased B. temperature is ... pressure is increased D. concentration is increased

If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion. (A) Film (B) Ash layer (C) Pore (D) None of these

Description : If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion. (A) Film (B) Ash layer (C) Pore (D) None of these

Last Answer : (A) Film

Non-catalytic fluid-solid reactions are represented by __________ model. (A) Continuous reaction (B) Unreacted core (C) Both (A) and (B) (D) Neither (A) and (B)

Description : Non-catalytic fluid-solid reactions are represented by __________ model. (A) Continuous reaction (B) Unreacted core (C) Both (A) and (B) (D) Neither (A) and (B)

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

For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption. (A) Physical (B) Chemical (C) Both (A) and (B) (D) Neither (A) nor (B)

Description : For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption. (A) Physical (B) Chemical (C) Both (A) and (B) (D) Neither (A) nor (B)

Last Answer : (B) Chemical

For the non catalytic reaction of particles with surrounding fluid, the same needed to achieve the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the __________ is the controlling resistance. (A) Film diffusion (B) Diffusion through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)

Description : For the non catalytic reaction of particles with surrounding fluid, the same needed to achieve the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the ... through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)

Last Answer : (C) Chemical reaction

For the non-catalytic reaction of particles with surrounding fluid, the time needed to achieve the same fractional conversion for particles of different but unchanging sizes is proportional to the square of particle diameter, when the __________ is the controlling resistance. (A) Film diffusion (B) Diffusion through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)

Description : For the non-catalytic reaction of particles with surrounding fluid, the time needed to achieve the same fractional conversion for particles of different but unchanging sizes is proportional to the square of particle diameter, ... through ash layer (C) Chemical reaction (D) Either (A), (B) or (C)

Last Answer : (B) Diffusion through ash layer

Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction?(A) Ash resistance (B) Gas film and pore surface diffusion resistances for reactants (C) Surface phenomenon resistance (D) Gas film and pore surface diffusion resistances for products

Description : Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction? (A) Ash resistance (B) Gas film and pore surface diffusion resistances for reactants (C) Surface phenomenon resistance (D) Gas film and pore surface diffusion resistances for products

Last Answer : (A) Ash resistance

Adsorption is a unit operation which generally involves __________ systems. (A) Liquid-solid (B) Gas-solid (C) Fluid-solid (D) Solid-solid

Description : Adsorption is a unit operation which generally involves __________ systems. (A) Liquid-solid (B) Gas-solid (C) Fluid-solid (D) Solid-solid

Last Answer : (C) Fluid-solid

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

What are the methods of treatment & disposal of radioactive wastes? (A) Evaporation & chemical precipitation (B) Biological methods & adsorption in ion exchange materials (C) Fixing into a solid mass with cement and sinking deep in the sea (D) All (A), (B) & (C)

Description : What are the methods of treatment & disposal of radioactive wastes? (A) Evaporation & chemical precipitation (B) Biological methods & adsorption in ion exchange materials (C) Fixing into a solid mass with cement and sinking deep in the sea (D) All (A), (B) & (C)

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

A catalyst loses its activity due to (A) Loss in surface area of the active component (B) Agglomeration of metal particles caused by thermal sintering of the solid surface (C) Covering of the catalytic active sites by a foreign substance (D) All (A), (B) and (C)

Description : A catalyst loses its activity due to (A) Loss in surface area of the active component (B) Agglomeration of metal particles caused by thermal sintering of the solid surface (C) Covering of the catalytic active sites by a foreign substance (D) All (A), (B) and (C)

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

In the fluid catalytic cracker (FCC), the cracking reaction is __________ (i) and the regeneration is__________ (ii) __________(A) (i) exothermic (ii) endothermic (B) (i) exothermic (ii) exothermic (C) (i) endothermic (ii) endothermic (D) (i) endothermic (ii) exothermic.

Description : In the fluid catalytic cracker (FCC), the cracking reaction is __________ (i) and the regeneration is__________ (ii) __________. (A) (i) exothermic (ii) endothermic (B) (i) exothermic (ii) exothermic (C) (i) endothermic (ii) endothermic (D) (i) endothermic (ii) exothermic

Last Answer : (D) (i) endothermic (ii) exothermic

If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst (A) Porosity is very important (B) Porosity is of less importance (C) Internal surface area is utilised efficiently (D) None of these

Description : If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst (A) Porosity is very important (B) Porosity is of less importance (C) Internal surface area is utilised efficiently (D) None of these

Last Answer : (B) Porosity is of less importance

The following statement relate to the adsorption of gases on a solid surface. Identify the incorrect statement among them :

Description : The following statement relate to the adsorption of gases on a solid surface. Identify the incorrect statement among them :

Last Answer : The following statement relate to the adsorption of gases on a solid surface. Identify the ... are increased D. Entropy of adsorption is negative

The correct statement(s) pertiaining to the adsorption of a gas on a solid surface is (are)

Description : The correct statement(s) pertiaining to the adsorption of a gas on a solid surface is (are)

Last Answer : The correct statement(s) pertiaining to the adsorption of a gas on a solid surface is (are) A. ... it is very slow due to higher energy of activation.

Finely divided catalyst has greater surface area and has greater catalytic activity than the compact solid. If a total surface area of 6291456 `cm^(2)

Description : Finely divided catalyst has greater surface area and has greater catalytic activity than the compact solid. If a total surface area of 6291456 `cm^(2)

Last Answer : Finely divided catalyst has greater surface area and has greater catalytic activity than the compact solid. If a total ... B. `80` C. `20` D. `22`

Catalytic action in a catalytic chemical reaction follows from the ability of catalyst to change the (A) Activation energy (B) Equilibrium constant (C) Heat of reaction (D) None of these

Description : Catalytic action in a catalytic chemical reaction follows from the ability of catalyst to change the (A) Activation energy (B) Equilibrium constant (C) Heat of reaction (D) None of these

Last Answer : (A) Activation energy

Pick out the wrong statement. (A) Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition (B) Alumina is added as a promoter to iron catalyst in ammonia synthesis reaction (C) Activation energy for a reaction is obtained from the intercept of the Arrhenius plot (D) Presence of inerts affects the equilibrium conversion of reactants in a chemical reaction

Description : Pick out the wrong statement. (A) Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition (B) Alumina is added as a promoter to ... Arrhenius plot (D) Presence of inerts affects the equilibrium conversion of reactants in a chemical reaction

Last Answer : (C) Activation energy for a reaction is obtained from the intercept of the Arrhenius plot

Pick out the wrong statement. (A) Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45°C(B) Most of the enzyme catalysed reactions involve at least two substrates (C) Enzymes help in increasing the activation energy of the reaction (D) Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & prod

Description : Pick out the wrong statement. (A) Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45°C ... in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & prod

Last Answer : (C) Enzymes help in increasing the activation energy of the reaction

Pick out the correct statement. (A) In catalytic reactions, the catalyst reacts with the reactants (B) A catalyst initiates a chemical reaction (C) A catalyst lowers the activation energy of the reacting molecules (D) A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction

Description : Pick out the correct statement. (A) In catalytic reactions, the catalyst reacts with the reactants (B) A catalyst initiates a chemical reaction (C) A catalyst lowers the activation energy of ... molecules (D) A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction

Last Answer : (C) A catalyst lowers the activation energy of the reacting molecules

Pick out the wrong statement. (A) 'Hold back' is defined as the fraction of material that stays longer than the mean residence time (B) Study of non-ideal flow reactor is done experimentally by stimulus￾response technique (C) For studying a chemical reaction, it is desirable to monitor the reactants during initial stages and the products during the final stages of reaction (D) A batch reactor cannot be used to study the kinetics of catalytic reaction

Description : Pick out the wrong statement. (A) 'Hold back' is defined as the fraction of material that stays longer than the mean residence time (B) Study of non-ideal flow reactor is done experimentally ... final stages of reaction (D) A batch reactor cannot be used to study the kinetics of catalytic reaction

Last Answer : (D) A batch reactor cannot be used to study the kinetics of catalytic reaction

The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst. (A) Increases (B) Decreases (C) Remain unaffected (D) Unpredictable from the data

Description : The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst. (A) Increases (B) Decreases (C) Remain unaffected (D) Unpredictable from the data

Last Answer : (C) Remain unaffected

For a heterogeneous catalytic reaction (A) Free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction (B) A relatively small amount of catalyst can cause the conversion of large amount of reactants which does not mean that catalyst concentration is important (C) The catalyst does not form an intermediate complex with the reactant (D) The surface of the catalyst does not play an important role during reaction

Description : For a heterogeneous catalytic reaction (A) Free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction (B) A relatively small amount of catalyst ... with the reactant (D) The surface of the catalyst does not play an important role during reaction

Last Answer : (A) Free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction

In the desorption of highly soluble gas from the liquid, the main resistance will be in the __________ phase. (A) Gas (B) Liquid (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : In the desorption of highly soluble gas from the liquid, the main resistance will be in the __________ phase. (A) Gas (B) Liquid (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (B) Liquid

The process employing desorption of the absorbed solute by a solvent is called (A) Elution (B) Osmosis (C) Reverse osmosis (D) Sublimation

Description : The process employing desorption of the absorbed solute by a solvent is called (A) Elution (B) Osmosis (C) Reverse osmosis (D) Sublimation

Last Answer : (A) Elution

A unit operation is exemplified by the process of (A) Reduction (B) Desorption (C) Nitration (D) Combustion

Description : A unit operation is exemplified by the process of (A) Reduction (B) Desorption (C) Nitration (D) Combustion

Last Answer : (B) Desorption

Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure? (A) Langmuir adsorption isotherm (B) Adsorption isobar (C) Freundlich adsorption isotherm (D) None of these

Description : Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure? (A) Langmuir adsorption isotherm (B) Adsorption isobar (C) Freundlich adsorption isotherm (D) None of these

Last Answer : (B) Adsorption isobar

Which of the following is incorrect about heterogeneous catalysis? a. The most effective catalysts are those which have small surface area b. Seperation of catlyst is easy c. Increase in the rate of reaction is due to decrease in the activation energy d. It is based upon the phenomenon of adsorption

Description : Which of the following is incorrect about heterogeneous catalysis? a. The most effective catalysts are those which have small surface area b. Seperation of catlyst is easy c. Increase in the rate of reaction is due to decrease in the activation energy d. It is based upon the phenomenon of adsorption

Last Answer : a. The most effective catalysts are those which have small surface area

Petroleum coke is commercially produced by the __________ process. (A) Hydrocracking (B) Visbreaking (C) Fluid catalytic cracking (D) Delayed coking

Description : Petroleum coke is commercially produced by the __________ process. (A) Hydrocracking (B) Visbreaking (C) Fluid catalytic cracking (D) Delayed coking

Last Answer : (D) Delayed coking

Which of the following processes consumes hydrogen? (A) Fluid catalytic cracking (B) Visbreaking (C) Propane deasphalting (D) None of these

Description : Which of the following processes consumes hydrogen? (A) Fluid catalytic cracking (B) Visbreaking (C) Propane deasphalting (D) None of these

Last Answer : (A) Fluid catalytic cracking

The main use of heavy gas oil produced by the vacuum distillation unit is as a (A) Blending component for kerosene (B) Blending component for petrol (C) Feedstock for fluid catalytic cracking unit (D) None of these

Description : The main use of heavy gas oil produced by the vacuum distillation unit is as a (A) Blending component for kerosene (B) Blending component for petrol (C) Feedstock for fluid catalytic cracking unit (D) None of these

Last Answer : (C) Feedstock for fluid catalytic cracking unit

The first step in infection of a host bacterial cells by a phage is A- adsorption B- absorption C- penetration D- replication

Description : The first step in infection of a host bacterial cells by a phage is A- adsorption B- absorption C- penetration D- replication

Last Answer : adsorption

'Lang factor' is defined as the ratio of the capital investment to the delivered cost of major equipments. The value of 'Lang factor' for fixed capital investment, for a solid-fluid processing chemical plant ranges from (A) 1.2 to 1.4 (B) 2.5 to 2.7 (C) 4.2 to 4.4 (D) 6.2 to 6.4

Description : 'Lang factor' is defined as the ratio of the capital investment to the delivered cost of major equipments. The value of 'Lang factor' for fixed capital investment, for a solid-fluid processing chemical plant ranges from (A) 1.2 to 1.4 (B) 2.5 to 2.7 (C) 4.2 to 4.4 (D) 6.2 to 6.4

Last Answer : C) 4.2 to 4.4

Defination of Desorption

Description : Defination of  Desorption

Last Answer : Desorption:- The process of removal of adsorbed substance from a surface of solid or liquid known as desorption.

Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the (A) Existence of thermal boundary layer (B) Temperature gradient produced due to density difference (C) Buoyancy of the bubbles produced at active nucleation site (D) None of these

Description : Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the (A) Existence of thermal boundary layer (B) Temperature gradient produced ... difference (C) Buoyancy of the bubbles produced at active nucleation site (D) None of these

Last Answer : (D) None of these

When a fluid flows over a solid surface, the (A) Velocity is uniform at any cross-section (B) Velocity gradient is zero at the solid surface (C) Resistance between the surface & the fluid is lesser as compared to that between the fluid layers themselves (D) Velocity is not zero at the solid surface

Description : When a fluid flows over a solid surface, the (A) Velocity is uniform at any cross-section (B) Velocity gradient is zero at the solid surface (C) Resistance between the surface & the fluid is lesser as compared to that between the fluid layers themselves (D) Velocity is not zero at the solid surface

Last Answer : (B) Velocity gradient is zero at the solid surface

Explain how the adsorption of gas on solid varies with : a. nature of adsorbate and adsorbent 

Description : Explain how the adsorption of gas on solid varies with : a. nature of adsorbate and adsorbent 

Last Answer : Explain how the adsorption of gas on solid varies with : a. nature of adsorbate and adsorbent b. surface area of adsorbent

Which of the following factors control the design of a fluid-solid reactor? (A) Reaction kinetics for single particle (B) Size distribution of solids being treated (C) Flow patterns of solids and fluid in the reactor (D) All (A), (B) and (C)

Description : Which of the following factors control the design of a fluid-solid reactor? (A) Reaction kinetics for single particle (B) Size distribution of solids being treated (C) Flow patterns of solids and fluid in the reactor (D) All (A), (B) and (C)

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

Chemisorption (chemical adsorption) is (A) Same as "Van der Waals" adsorption (B) Characterised by adsorption of heat (C) An irreversible phenomenon (D) A reversible phenomenon

Description : Chemisorption (chemical adsorption) is (A) Same as "Van der Waals" adsorption (B) Characterised by adsorption of heat (C) An irreversible phenomenon (D) A reversible phenomenon

Last Answer : (C) An irreversible phenomenon

Which is the best and the most effective method for the removal of organic contaminant present in the polluted water in very small quantity (say < 200 mg/litre)? (A) Lagooning (B) Activated carbon adsorption (C) Biological oxidation pond (D) Chemical coagulation

Description : Which is the best and the most effective method for the removal of organic contaminant present in the polluted water in very small quantity (say < 200 mg/litre)? (A) Lagooning (B) Activated carbon adsorption (C) Biological oxidation pond (D) Chemical coagulation

Last Answer : (B) Activated carbon adsorption

In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is (A) Equal to the heat of formation of surface compound (B) Equal to the heat of wetting (C) Zero (D) Called integral heat of adsorption

Description : In case of physical adsorption, the difference between heat of adsorption and heat of normal condensation is (A) Equal to the heat of formation of surface compound (B) Equal to the heat of wetting (C) Zero (D) Called integral heat of adsorption

Last Answer : (B) Equal to the heat of wetting

In Langmuir treatment of adsorption, (A) Whole surface of the catalyst does not have the same activity for adsorption and there is attraction between the adsorbed molecule (B) Whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site (C) All the adsorption does not take place by the same mechanism (D) Extent of adsorption is more than one complete monomolecular layer on the surface

Description : In Langmuir treatment of adsorption, (A) Whole surface of the catalyst does not have the same activity for adsorption and there is attraction between the adsorbed molecule (B) Whole surface of ... same mechanism (D) Extent of adsorption is more than one complete monomolecular layer on the surface

Last Answer : (B) Whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site

Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates is not used to derive BET equation? (A) Langmuir's assumption applies to every adsorbed layer (B) There is no dynamic equilibrium between successive layer (C) The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer (except the first one) is involved in each of the evaporation process (D) None of these

Description : Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates ... (except the first one) is involved in each of the evaporation process (D) None of these

Last Answer : (B) There is no dynamic equilibrium between successive layer