Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 9

The units of frequency factor in Arhenious equation:


Options are :

  • Depend on temperature, pressure etc. of the reaction
  • Depend on the order of the reaction
  • Are cycles per unit time
  • Are the same as those of the rate constant

Answer :Are the same as those of the rate constant

Signal normally used to study non-ideal flow by stimulus response technique is __________ input


Options are :

  • None of these
  • Pulse
  • Step

Answer :Pulse Step

For a vapour phase catalytic reaction (A + B

P) which follows the Ridel mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction rate is irreversible, product also absorbs)


A.


B.


C.


D.


Options are :

  • C
  • B
  • D
  • A

Answer :A

For a gaseous phase reaction, rate of reaction is equal to K. CA . CB. If the volume of the reactor is suddenly reduced to l/4th of its initial volume, then the rate of reaction compared to the original rate will be __________ times


Options are :

  • 16
  • 1/8
  • 1/16
  • 8

Answer :16

Which of the following is not a chemical step in a fluid solid catalytic reaction ?


Options are :

  • Surface chemical reaction
  • Adsorption
  • None of these
  • Desorption

Answer :None of these

__________ is the response curve for a step input signal from a reactor


Options are :

  • C-curve
  • S-curve
  • None of these
  • I-curve

Answer :S-curve

The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst


Options are :

  • Remains unaffected
  • Decreases
  • Increases
  • Unpredictable from the data

Answer :Remains unaffected

For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption


Options are :

  • Neither A nor B
  • Both A and B
  • Chemical
  • Physical

Answer :Chemical

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 1

If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion


Options are :

  • None of these
  • Film
  • Pore
  • Ash layer

Answer :Film

A catalyst loses its activity due to:


Options are :

  • Agglomeration of metal particles caused by thermal sintering of the solid surface
  • Loss in surface area of the active component
  • All of these
  • Covering of the catalytic active sites by a foregin substance

Answer :All of these

At a given value of E/R (ratio of activation energy and gas constant), the ratio of the rate constants at 500K and 400K is 2, if Arrhenious law is used.

What will be this ratio, if transition state theory is used with the same value of E/R ?


Options are :

  • 2
  • 2.24
  • 2.5
  • 1.6

Answer :2.5

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 10

When a catalyst increases the rate of forward reaction, the value of rate constant:


Options are :

  • Becomes infinite
  • Decreases
  • Remain same
  • Increases

Answer :Increases

In case of physical adsorption, the heat of adsorption is of the order of __________ kcal/kg.mole


Options are :

  • 1000
  • 100000
  • 100
  • 10000

Answer :1000

B.E.T. method can be used to determine the __________ of a porous catalyst


Options are :

  • Solid density
  • Pore volume
  • Surface area
  • All of these

Answer :Surface area

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 11

Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature ?


Options are :

  • Time
  • None of these
  • Diameter of the reactor
  • Useful volume of the tank

Answer :Time

A high space velocity means that a given:


Options are :

  • None of these
  • Conversion can be obtained with a high feed rate
  • Reaction can be accomplished with small reactor

Answer :Conversion can be obtained with a high feed rate Reaction can be accomplished with small reactor

A first order reaction requires two unequal sized CSTR. Which of the following gives higher yield ?


Options are :

  • Either of the arrangement A or B will give the same yield
  • Smaller reactor followed by larger one
  • Large reactor followed by smaller one
  • Data insufficient, can't be predicted

Answer :Either of the arrangement A or B will give the same yield

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 2

What is the order of a chemical reaction,

, if the rate of formation of 'C', increases by a factor of 2.82 on doubling the concentration of 'A' and increases by a factor of 9 on trebling the concentration of 'B'?


Options are :

  • 5/4
  • 5/2
  • 7/2
  • 7/4

Answer :7/2

The rate constant of a chemical reaction decreases by decreasing the:


Options are :

  • Concentration of reactants
  • Duration of reaction
  • Temperature
  • Pressure

Answer :Temperature

__________ explains the mechanism of catalysis


Options are :

  • Thermodynamics
  • Collision theory
  • Activated complex theory
  • None of these

Answer :Activated complex theory

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 3

The rate constant of a chemical reaction increases by 100 times when the temperature is increased from 400 K to 500 K. Assuming transition state theory is valid, the value of E/R is:


Options are :

  • 8987K
  • 8621K
  • 8764K
  • 9210K

Answer :9210K

In a consecutive reaction system

when E1 is much greater than E2, the yield of B increases with the:


Options are :

  • Increase in initial concentration of A
  • Decrease of temperature
  • Decrease in initial concentration of A
  • Increase of temperature

Answer :Increase of temperature

6 gm of carbon is burnt with an amount of air containing 18 gm oxygen. The product contains 16.5 gms CO2 and 2.8 gms CO besides other constituents. What is the degree of conversion on the basis of disappearance of limiting reactant ?


Options are :

  • 100%
  • 75%
  • 20%
  • 95%

Answer :95%

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 4

Catalyst carriers:


Options are :

  • Increase the activity of a catalyst
  • Have very high selectivity
  • Provide large surface area with a small amount of active material
  • Inhibit catalyst poisoning

Answer :Provide large surface area with a small amount of active material

Specific rate constant for a second order reaction:


Options are :

  • Varies with temperature
  • None of these
  • Depends on the nature of the reactants
  • Is independent of temperature

Answer :Varies with temperature Depends on the nature of the reactants

If in the gaseous phase reaction, N2O4

2NO2, x is the part of N2O4 which dissociates, then the number of molecules at equilibrium will be:


Options are :

  • (1 + x)^(2)
  • (1 + x)
  • (1 - x)^(2)
  • (1 - x)

Answer :(1 + x)

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 5

Pick out the wrong statement pertaining to space velocity of flow reactors:


Options are :

  • The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor
  • The space velocity of 3 hr-1 means that three reactor volumes of feed at specified conditions are being fed into the reactor every hour
  • None of these
  • The unit of space velocity is (time)-1

Answer :The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor

For every 10C rise in temperature, the rate of chemical reaction doubles. When the temperature is increased from 30 to 70C, the rate of reaction increases __________ times


Options are :

  • 8
  • 32
  • 12
  • 16

Answer :16

Conversion increases with increase in temperature in case of a an __________ reaction


Options are :

  • Irreversible
  • Reversible endothermic
  • Reversible exothermic
  • Autocatalytic

Answer :Reversible endothermic

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 6

The catalyst in a second order reversible reaction increases the rate of the forward reaction:


Options are :

  • only
  • and backward reaction equally
  • and decreases that of backward reaction
  • to a greater extent than that of the backward reaction

Answer :and backward reaction equally

Rate of a gaseous phase reaction is given by,

. The unit of rate constant is:


Options are :

  • (hr)-1
  • atm.(hr)-1
  • (atm)-1.(hr)-1
  • (atm)-1

Answer :(atm)-1.(hr)-1

The reason why a catalyst increases the rate of reaction is that, it:


Options are :

  • Increases the activation energy
  • Decreases the molecular collision diameter
  • None of these
  • Decreases the energy barrier for reaction

Answer :Decreases the energy barrier for reaction

Radioactive decay follows __________ order kinetics


Options are :

  • Zero
  • Third
  • Second
  • First

Answer :First

BET apparatus:


Options are :

  • Is made entirely of stainless steel
  • Operates at very high pressure
  • None of these
  • Measures the catalyst surface area directly

Answer :None of these

For a reaction of the type,

, the rate of reaction (- rx) is given by:


Options are :

  • (K1+K1)CX
  • (K1-K2)CX
  • (K1+K2+K3)CX
  • K1CV - K2CX

Answer :K1CV - K2CX

At a given temperature, K1, K2 and K3 are equilibrium constants for the following reactions 1, 2, 3 respectively.


CH4(g) + H2O(g)

CO(g) + 3H2(g),


CO(g) + H2O(g)

CO2(g) + H2(g)


CH4(g) + 2H2O(g)

CO2(g) + 4H2(g)


Then K1, K2 and K3 are related as:


Options are :

  • K3 = (K1.K2)^(2)
  • K3 = (K1.K2)^(0.5)
  • K3(K1+K2)/2
  • K3 = K1.K2

Answer :K3 = K1.K2

The rate of a chemical reaction is almost doubled for every 10C rise in temperature. The rate will increase __________ times, if the temperature rises form 10 to 100C


Options are :

  • 256
  • 612
  • 112
  • 512

Answer :512

For a zero order chemical reaction, the:


Options are :

  • Products concentration increases linerarly with time
  • Half life period is directly proportion to the initial concentration of the reac-tants
  • Plot of products concentration with time is a straight line through the origin
  • All of these

Answer :All of these

Space velocity:


Options are :

  • Is a measure of the ease of the reaction
  • All of these
  • Is the maximum feed rate pre unit volume of reactor for a given conversion
  • Describes the extensive operating characteristics of a tubular flow reactor

Answer :All of these

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


Options are :

  • Non-elementary
  • Multiple
  • Autocatalytic
  • Elementary

Answer :Non-elementary

If the rate of a chemical reaction becomes slower at a given temperature, then the:


Options are :

  • Entropy changes
  • Free energy of activation is higher
  • Free energy of activation is lower
  • Initial concentration of the reactants remains constant

Answer :Free energy of activation is higher

Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure ?


Options are :

  • Langmuir adsorption isotherm
  • Freundlich adsorption isotherm
  • None of these
  • Adsorption isobar

Answer :Adsorption isobar

Pick out the wrong statement:


Options are :

  • Enzymes help in increasing the activation energy of the reaction
  • Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & products
  • Most of the enzyme catalysed reactions involve at least two substrates
  • Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45C

Answer :Enzymes help in increasing the activation energy of the reaction

A batch reactor is:


Options are :

  • Most suitable for very large production rate
  • Suitable for gas-phase reactions on commercial scale
  • Least expensive to operate for a given rate
  • Suitable for liquid phase reactions involving small production rate

Answer :Suitable for liquid phase reactions involving small production rate

Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction ?


Options are :

  • Surface phenomenon resistance
  • Ash resistance
  • Gas film and pore surface diffusion resistances for products
  • Gas film and pore surface diffusion resistances for reactants

Answer :Ash resistance

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