27 real Chemical Reaction Engineering questions from the Chemical Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Arrhenius equation?
Junior
A.steady-state mole balance V/F_A0 = X/(−r_A) evaluated at outlet conditions, since the whole vessel sits at exit composition
B.rate constant rises exponentially with temperature as k = A·exp(−E/RT); activation energy comes from the slope of ln k against 1/T
C.time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
D.exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
2. Which term means: "rate constant rises exponentially with temperature as k = A·exp(−E/RT); activation energy comes from the slope of ln k against 1/T"?
A.Arrhenius equation — ratio of actual rate in a catalyst pellet to the rate if the whole interior were at surface concentration; it falls as the Thiele modulus rises
B.Arrhenius equation — reactor volume divided by volumetric feed rate, the time needed to process one reactor volume of feed at inlet conditions
C.Arrhenius equation — condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve
D.Arrhenius equation — rate constant rises exponentially with temperature as k = A·exp(−E/RT); activation energy comes from the slope of ln k against 1/T
A.time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
B.condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve
C.exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
D.ratio of actual rate in a catalyst pellet to the rate if the whole interior were at surface concentration; it falls as the Thiele modulus rises
A.Half-life of a first-order reaction — for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration
B.Half-life of a first-order reaction — ratio of actual rate in a catalyst pellet to the rate if the whole interior were at surface concentration; it falls as the Thiele modulus rises
C.Half-life of a first-order reaction — time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
D.Half-life of a first-order reaction — rate constant rises exponentially with temperature as k = A·exp(−E/RT); activation energy comes from the slope of ln k against 1/T
A.time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
B.for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration
C.exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
D.condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve
11. Which term means: "for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration"?
A.CSTR vs PFR volume — ratio of reaction rate to convective transport rate; large values mean conversion is limited by transport rather than kinetics
B.CSTR vs PFR volume — steady-state mole balance V/F_A0 = X/(−r_A) evaluated at outlet conditions, since the whole vessel sits at exit composition
C.CSTR vs PFR volume — time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
D.CSTR vs PFR volume — for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration
A.rate constant rises exponentially with temperature as k = A·exp(−E/RT); activation energy comes from the slope of ln k against 1/T
B.condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve
C.time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
D.steady-state mole balance V/F_A0 = X/(−r_A) evaluated at outlet conditions, since the whole vessel sits at exit composition
A.CSTR design equation — for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration
B.CSTR design equation — exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
C.CSTR design equation — ratio of reaction rate to convective transport rate; large values mean conversion is limited by transport rather than kinetics
D.CSTR design equation — steady-state mole balance V/F_A0 = X/(−r_A) evaluated at outlet conditions, since the whole vessel sits at exit composition
A.time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
B.for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration
C.exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
D.ratio of reaction rate to convective transport rate; large values mean conversion is limited by transport rather than kinetics
17. Which term means: "ratio of reaction rate to convective transport rate; large values mean conversion is limited by transport rather than kinetics"?
A.Damköhler number — exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
B.Damköhler number — for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration
C.Damköhler number — reactor volume divided by volumetric feed rate, the time needed to process one reactor volume of feed at inlet conditions
D.Damköhler number — ratio of reaction rate to convective transport rate; large values mean conversion is limited by transport rather than kinetics
A.time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
B.exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
C.condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve
D.steady-state mole balance V/F_A0 = X/(−r_A) evaluated at outlet conditions, since the whole vessel sits at exit composition
A.Residence time distribution — steady-state mole balance V/F_A0 = X/(−r_A) evaluated at outlet conditions, since the whole vessel sits at exit composition
B.Residence time distribution — rate constant rises exponentially with temperature as k = A·exp(−E/RT); activation energy comes from the slope of ln k against 1/T
C.Residence time distribution — exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
D.Residence time distribution — ratio of actual rate in a catalyst pellet to the rate if the whole interior were at surface concentration; it falls as the Thiele modulus rises
A.ratio of actual rate in a catalyst pellet to the rate if the whole interior were at surface concentration; it falls as the Thiele modulus rises
B.for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration
C.ratio of reaction rate to convective transport rate; large values mean conversion is limited by transport rather than kinetics
D.exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
23. Which term means: "ratio of actual rate in a catalyst pellet to the rate if the whole interior were at surface concentration; it falls as the Thiele modulus rises"?
A.Effectiveness factor — time to consume half the reactant, equal to 0.693/k and independent of the initial concentration
B.Effectiveness factor — condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve
C.Effectiveness factor — ratio of actual rate in a catalyst pellet to the rate if the whole interior were at surface concentration; it falls as the Thiele modulus rises
D.Effectiveness factor — for a positive-order reaction a plug-flow reactor needs less volume than a mixed reactor at the same conversion because it works at higher average concentration
A.reactor volume divided by volumetric feed rate, the time needed to process one reactor volume of feed at inlet conditions
B.steady-state mole balance V/F_A0 = X/(−r_A) evaluated at outlet conditions, since the whole vessel sits at exit composition
C.ratio of reaction rate to convective transport rate; large values mean conversion is limited by transport rather than kinetics
D.condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve
26. Which term means: "condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve"?
A.Thermal runaway — ratio of reaction rate to convective transport rate; large values mean conversion is limited by transport rather than kinetics
B.Thermal runaway — condition where heat release outruns cooling so temperature and rate climb together; avoided by keeping the heat-removal line steeper than the heat-generation curve
C.Thermal runaway — exit-age distribution E(t) from a tracer pulse, used to diagnose dead zones, bypassing and channelling in real reactors
D.Thermal runaway — steady-state mole balance V/F_A0 = X/(−r_A) evaluated at outlet conditions, since the whole vessel sits at exit composition
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