8247 + Mcqs in Chemical Engineering Page 98 McqOptions

4851.	Which of the following is a characteristic of an ideal plug flow reactor ?
A.	Axial dispersion
B.	Flat velocity profile
C.	Uniform mixing
D.	None of these
Answer» C. Uniform mixing

Discussion

4852.	Velocity of a reaction depends upon the
A.	nature of the reactants.
B.	concentration of the reactants.
C.	temperature at which the reaction is carried.
D.	all (a), (b) and (c).
Answer» E.

Discussion

4853.	Threshold energy in a reaction is equal to the
A.	activation energy
B.	normal energy of reactants
C.	sum of (a) & (b)
D.	neither (a) nor (b)
Answer» D. neither (a) nor (b)

Discussion

4854.	Second order consecutive irreversible reactions were carried out in a constant volume isothermal batch reactor with different initial feed compositions. Reactor temperature was same in all the cases. In experiments where the ratio of concentration of B to that of A in the initial feed was less than 0.5, the concentration of B increased first, reached a maximum and then declined with time. However, for all experiments where this concentration ratio was 0.5 or above, concentration of B decreased monotonically with time right from the beginning. What is the ratio of the two rate constants (k1/k2)?
A.	1/4
B.	1/2
C.	2
D.	4
Answer» B. 1/2

Discussion

4855.	There is no correspondence between stoichiometry and the rate equation in case of a/an __________ reaction.
A.	elementary
B.	multiple
C.	autocatalytic
D.	non-elementary
Answer» E.

Discussion

4856.	A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?
A.	Inner catalyst core of radius R/8 does not participate in reaction.
B.	Inner catalyst core of radius R/2 does not participate in reaction.
C.	Inner catalyst core of radius 7R/8 does not participate in reaction.
D.	Effectiveness factor for a zero order reaction can not be 7/8 as it must always be 1.
Answer» B. Inner catalyst core of radius R/2 does not participate in reaction.

Discussion

4857.	In the reversible reaction of the type, A + B AB, in general
A.	both forward and backward reactions will be exothermic.
B.	neither of the reactions will be en-dothermic.
C.	the combination reaction will be exothermic, while the dissociation reaction will be endothermic.
D.	the combination reaction will be endothermic, while the dissociation reaction will be exothermic.
Answer» D. the combination reaction will be endothermic, while the dissociation reaction will be exothermic.

Discussion

4858.	A batch reactor is
A.	suitable for gas-phase reactions on commercial scale.
B.	suitable for liquid phase reactions involving small production rate.
C.	least expensive to operate for a given rate.
D.	most suitable for very large production rate.
Answer» C. least expensive to operate for a given rate.

Discussion

4859.	For a first order reaction carried out in a plug flow reactor, the space time is
A.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/460-317-1.png">
B.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/460-317-2.png">
C.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/460-317-3.png">
D.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/460-317-4.png">
Answer» B. <img src="/_files/images/chemical-engineering/chemical-reaction-engineering/460-317-2.png">

Discussion

4860.	For an isothermal second order aqueous phase reaction, A B, the ratio of the time required for 90% conversion to the time required for 45% conversion is
A.	2
B.	4
C.	11
D.	22
Answer» D. 22

Discussion

4861.	Photochemical reaction rate does not depend significantly on temperature, because
A.	it is a reversible reaction.
B.	it is an exothermic reaction.
C.	the energy of reacting molecules exceeds the activation energy by absorption of light.
D.	none of these.
Answer» D. none of these.

Discussion

4862.	A CSTR is to be designed in which an exothermic liquid phase first order reaction of the type, A R, is taking place. The reactor is to be provided with a jacket in which coolant is flowing. Following data is given: CA0= 5 kmole/m3 ; XA = 0.5; Feed temperature = reactor temperature = 40 C. Rate constant at 40 C = 1 min-1 ; ( H) = - 40kJ/mole; = 1000kg/m3 CP = 4 J/gm. C ; q = 10-3 m3/min ( and CP are same for the reactant and product streams). The amount of heat to be removed is
A.	2/3 kW
B.	1kW
C.	5/3 kW
D.	4kW
Answer» D. 4kW

Discussion

4863.	According to the 'law of mass action', the rate of reaction is directly proportional to the
A.	equilibrium constant.
B.	volume of the reaction vessel.
C.	nature of the reactants.
D.	molar concentration of the reactants.
Answer» E.

Discussion

4864.	In a chemical reaction, __________ are conserved.
A.	ions
B.	masses
C.	atoms
D.	both(b) & (c)
Answer» E.

Discussion

4865.	For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant
A.	is independent of pressure.
B.	increases with pressure.
C.	decreases with pressure.
D.	increases /decreases with pressure depending on the stoichiometric co-efficients of the reaction.
Answer» C. decreases with pressure.

Discussion

4866.	Which of the following is a controlling factor in very fast heterogeneous reaction ?
A.	Heat and mass transfer effects
B.	Pressure
C.	Temperature
D.	Composition of reactant
Answer» B. Pressure

Discussion

4867.	Enzymes are destroyed, when the
A.	temperature is very high,
B.	reactant's concentration is very high.
C.	reactant's concentration is very low.
D.	reaction rate is independent of the reactant's concentration.
Answer» B. reactant's concentration is very high.

Discussion

4868.	For an autocatalytic reactor, the suitable reactor set up is
A.	P.F. reactors in series.
B.	CSTR in series.
C.	CSTR followed by P.F. reactor.
D.	P.F. reactor followed by CSTR.
Answer» D. P.F. reactor followed by CSTR.

Discussion

4869.	Ionic reactions occur in
A.	solid state only
B.	liquid state only
C.	solutions
D.	any state
Answer» D. any state

Discussion

4870.	Sometimes, batch process is preferred over continuous process, when the product
A.	quality & yield can not be achieved in continuous processes, because of long residence time.
B.	sales demand is fluctuating.
C.	both (a) & (b).
D.	neither (a) nor (b).
Answer» D. neither (a) nor (b).

Discussion

4871.	The reaction A B is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m3 is fed to the reactor at the rate of 0.01 m3 /s and at a temperature of 500 K. If the exit conversion is 20%, then the exit temperature (in k)is (Data: Heat of reaction at 298 K = - 50000 kJ/ kmole of A reacted Heat capacities CPA = CPB = 100kJ/kmole. K (may be assumed to be independent of temperature))
A.	400
B.	500
C.	600
D.	1000
Answer» D. 1000

Discussion

4872.	Which of the following is not a theory of homogeneous reaction?
A.	Collision theory and activated complex theory
B.	Chain reaction theory
C.	Radiation hypothesis
D.	None of these
Answer» E.

Discussion

4873.	A first order homogeneous reaction of the type X Y Z (consecutive reaction) is carried out in a CSTR. Which of the following curves respectively show the variation of the concentration of X, Y and Z with time?
A.	I, II, III
B.	III, II, I
C.	III, I, II
D.	II, III, i
Answer» C. III, I, II

Discussion

4874.	In a semi-batch reactor,
A.	mixing takes place in axial direction only.
B.	velocity of reaction can be controlled.
C.	condition similar to plug flow reactor exists.
D.	residence time is constant.
Answer» C. condition similar to plug flow reactor exists.

Discussion

4875.	Most important characteristics of gas-liquid reactors are the
A.	specific inter-facial area
B.	liquid hold-up
C.	both (a) and (b)
D.	none of these
Answer» D. none of these

Discussion

4876.	The conversion for a second order, irreversible reaction (constant volume), , in batch mode is given by
A.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/475-469-2.png">
B.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/475-469-3.png">
C.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/475-469-4.png">
D.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/475-469-5.png">
Answer» C. <img src="/_files/images/chemical-engineering/chemical-reaction-engineering/475-469-4.png">

Discussion

4877.	The ratio of moles of a reactant converted into the desired product to that converted into unwanted product is called
A.	operational yield
B.	relative yield
C.	selectivity
D.	none of these
Answer» D. none of these

Discussion

4878.	A trickle bed reactor is the one, which
A.	has altogether three streams either entering or leaving.
B.	processes three reactants at different flow rates.
C.	processes three reactants with same flow rate.
D.	employs all the three phases (i.e.. .solid, liquid and gas).
Answer» E.

Discussion

4879.	What is the order of a chemical reaction in which doubling the initial concentration of the reactants doubles the half life time of the reaction ?
A.	0
B.	1
C.	2
D.	3
Answer» B. 1

Discussion

4880.	The excess energy of the reactants required to dissociate into products is known as the __________ energy.
A.	thermal
B.	activation
C.	threshold
D.	binding
Answer» C. threshold

Discussion

4881.	In a/an __________ vessel, the fluid enters and leaves following plug flow.
A.	open
B.	closed
C.	open-closed
D.	close-opened
Answer» C. open-closed

Discussion

4882.	In solid catalysed reactions the diffusional effects are more likely to affect the overall rate of reaction for
A.	fast reactions in catalyst of small pore diameter.
B.	fast reaction in catalyst of large pore diameter.
C.	slow reactions in catalyst of small pore diameter.
D.	slow reactions in catalyst of large pore diameter.
Answer» D. slow reactions in catalyst of large pore diameter.

Discussion

4883.	Helium-mercury method can be used to determine the __________ of the catalyst particle.
A.	pore volume
B.	solid density
C.	porosity
D.	all (a), (b), & (c).
Answer» E.

Discussion

4884.	For the chemical reaction X Y, it is observed that, on doubling the concentration of 'X', the reaction rate quadruples. If the reaction rate is proportional to Cxn, then what is the value of 'n' ?
A.	4
B.	1/4
C.	16
D.	2
Answer» B. 1/4

Discussion

4885.	Chemical reaction rate of a component depends upon the
A.	composition of the component only.
B.	temperature of the system.
C.	pressure of the system.
D.	all (a), (b) and (c).
Answer» E.

Discussion

4886.	In a semi-batch reactor
A.	velocity of reaction can be controlled.
B.	maximum conversion can be controlled.
C.	both the reactants flow counter-currently.
D.	residence time is constant.
Answer» B. maximum conversion can be controlled.

Discussion

4887.	In a reversible reaction, a catalyst increases the rate of forward reaction
A.	only.
B.	to a greater extent than that of the backward reaction.
C.	and decreases that of the backward reaction.
D.	and the backward reaction equally.
Answer» E.

Discussion

4888.	Maximum equilibrium conversion for endothermic reaction is obtained at the __________ temperature.
A.	highest possible
B.	lowest possible
C.	intermediate
D.	room
Answer» B. lowest possible

Discussion

4889.	When an exothermic reversible reaction is conducted adiabatically, the rate of reaction
A.	continuously increases.
B.	continuously decreases.
C.	passes through a maximum.
D.	passes through a minimum.
Answer» D. passes through a minimum.

Discussion

4890.	For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to
A.	1
B.	0.5
C.	0.1
D.	0
Answer» D. 0

Discussion

4891.	The eddy diffusivity for a liquid in plug flow must be
A.	1
B.	0
C.
D.	between 0 and 1
Answer» C.

Discussion

4892.	For multiple reactions, the flow pattern within the vessel affects the
A.	size requirement
B.	distribution of reaction products
C.	both (a) and (b)
D.	neither (a) nor (b)
Answer» D. neither (a) nor (b)

Discussion

4893.	The rate expression for the gaseous phase reaction, CO + 2H2 CH3OH, is given by, . Which of the following is not possible ?
A.	= 1, = 1, =1
B.	= 1, = 2, = 1
C.	= 1/3, = 2/3, = 1/3
D.	= 1/2, = 1, = 1/2
Answer» B. = 1, = 2, = 1

Discussion

4894.	The importance of diffusion in a catalyst are increased by
A.	large catalyst particle size.
B.	an active surface of the catalyst.
C.	small pore diameter.
D.	all (a), (b) and (c).
Answer» E.

Discussion

4895.	A back mix reactor is
A.	suitable for gas phase reactions.
B.	ideal at very low conversion.
C.	same as plug flow reactor (PFR).
D.	same as ideal stirred tank reactor.
Answer» E.

Discussion

4896.	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
Answer» C. Ash layer diffusion

Discussion

4897.	For a __________ order chemical reaction, , the half life period is independent of the initial concentration of the reactant A.
A.	zero
B.	first
C.	second
D.	third
Answer» C. second

Discussion

4898.	The rate controlling step for the heterogeneous irreversible catalytic reaction A(g) + B(g) C(g) is the surface reaction of absorbed A with absorbed B to give adsorbed C. The rate expression for this reaction can then be written as (where, KA, KB and KC are the equilibrium constants and is the rate constant of the rate controlling step.)
A.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/470-420-1.png">
B.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/470-420-2.png">
C.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/470-420-3.png">
D.	<img src="/_files/images/chemical-engineering/chemical-reaction-engineering/470-420-4.png">
Answer» E.

Discussion

4899.	The optimum performance for reactors operating in parallel is obtained when the feed stream is distributed in such a way, that the
A.	space time for each parallel line is same.
B.	space time for parallel lines is different.
C.	larger reactors have more space time compared to smaller ones.
D.	none of these.
Answer» B. space time for parallel lines is different.

Discussion

4900.	A catalyst is said to be a negative catalyst, ifit
A.	retards the rate of reaction.
B.	reduces the value of equilibrium constant.
C.	does not initiate the reaction.
D.	all (a), (b) and (c).
Answer» B. reduces the value of equilibrium constant.

Discussion

Explore topic-wise MCQs in Engineering.

Which of the following is a characteristic of an ideal plug flow reactor ?

Velocity of a reaction depends upon the

Threshold energy in a reaction is equal to the

There is no correspondence between stoichiometry and the rate equation in case of a/an __________ reaction.

In the reversible reaction of the type, A + B AB, in general

A batch reactor is

For a first order reaction carried out in a plug flow reactor, the space time is

For an isothermal second order aqueous phase reaction, A B, the ratio of the time required for 90% conversion to the time required for 45% conversion is

Photochemical reaction rate does not depend significantly on temperature, because

According to the 'law of mass action', the rate of reaction is directly proportional to the

In a chemical reaction, __________ are conserved.

For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant

Which of the following is a controlling factor in very fast heterogeneous reaction ?

Enzymes are destroyed, when the

For an autocatalytic reactor, the suitable reactor set up is

Ionic reactions occur in

Sometimes, batch process is preferred over continuous process, when the product

Which of the following is not a theory of homogeneous reaction?

A first order homogeneous reaction of the type X Y Z (consecutive reaction) is carried out in a CSTR. Which of the following curves respectively show the variation of the concentration of X, Y and Z with time?

In a semi-batch reactor,

Most important characteristics of gas-liquid reactors are the

The conversion for a second order, irreversible reaction (constant volume), , in batch mode is given by

The ratio of moles of a reactant converted into the desired product to that converted into unwanted product is called

A trickle bed reactor is the one, which

What is the order of a chemical reaction in which doubling the initial concentration of the reactants doubles the half life time of the reaction ?

The excess energy of the reactants required to dissociate into products is known as the __________ energy.

In a/an __________ vessel, the fluid enters and leaves following plug flow.

In solid catalysed reactions the diffusional effects are more likely to affect the overall rate of reaction for

Helium-mercury method can be used to determine the __________ of the catalyst particle.

For the chemical reaction X Y, it is observed that, on doubling the concentration of 'X', the reaction rate quadruples. If the reaction rate is proportional to Cxn, then what is the value of 'n' ?

Chemical reaction rate of a component depends upon the

In a semi-batch reactor

In a reversible reaction, a catalyst increases the rate of forward reaction

Maximum equilibrium conversion for endothermic reaction is obtained at the __________ temperature.

When an exothermic reversible reaction is conducted adiabatically, the rate of reaction

For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to

The eddy diffusivity for a liquid in plug flow must be

For multiple reactions, the flow pattern within the vessel affects the

The rate expression for the gaseous phase reaction, CO + 2H2 CH3OH, is given by, . Which of the following is not possible ?

The importance of diffusion in a catalyst are increased by

A back mix reactor is

Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature?

For a __________ order chemical reaction, , the half life period is independent of the initial concentration of the reactant A.

The optimum performance for reactors operating in parallel is obtained when the feed stream is distributed in such a way, that the

A catalyst is said to be a negative catalyst, ifit