CRE section 4

Question 1

not involved in a gas phase catalytic rxn

Answer 1

ash resistance

Question 2

if the time required to change the concentration of reactant to its original value is independent of the initial concentration, the order is

Answer 2

one

Question 3

a batch adiabatic reqctor at an initual temp of 373 is being used for the rxn A -> B. the temp rise after a conversion of 0.5 will be

Answer 3

10°C

Question 4

if CA is the quantity of reactants initially present, the quantity left after n half period will be equal to

Answer 4

(1/2)^n.CA

Question 5

a photochemical rxn is

Answer 5

initiated by light

Question 6

the rate controlling step for the heterogeneous irreversible catalytic rxn is the surface rxn absorbed A with absorbed B to give absorbed C. the rate expression for this rxn can be written as (pic)

Answer 6

(pic)

Question 7

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

Answer 7

space time for each parallel line is same

Question 8

a catalyst is said to be a negative catalyst if it

Answer 8

retards the rate of rxn

Question 9

for the non catalytic rxn 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

Answer 9

chemical rxn

Question 10

pure ethanol vapor is fed to a reactor packed with alumina catalyst at the rate of 100kmole / hr. the percent conversion of ethanol in the reactor is

Answer 10

100

Question 11

the conversion for a second order irreversible rxn in batch mode is given by (pic)

Answer 11

pic

Question 12

wrong statement (when the rxn rate)

Answer 12

when the rxn rate is independent of temperature, then order rxn is said to be of zero order

Question 13

a backmix reactor

Answer 13

is same as ideal stirred tank reactor

Question 14

rate of chemicla rxn is not influenced by the

Answer 14

number of molecules of reactant taking part in a rxn

Question 15

wrong statement (residence time)

Answer 15

residence time for all the elements of fluid in case of PFR need not be same

Question 16

the rxn AB is conducted in an adiabatic pfr. if the exit conversion is 20% then the exit temperature is

Answer 16

600

Question 17

which is not a theory of homogeneous rxn

Answer 17

none if these

Question 18

a first order homogeneous rxn of the type XYZ is carried out in a CSTR, which of the following curves respectively show the variation of the conc xyz with time

Answer 18

iii, ii, i

Question 19

in a semi- batch reactor

Answer 19

velocity of rxn can be controlled

Question 20

most important characteristics of gas-liquid reactors are the

Answer 20

both a and b

Question 21

controlling factor in very fast heterogeneous rxn

Answer 21

heat and mass transfer effects

Question 22

enzymes are destroyed when the

Answer 22

temperature is very high

Question 23

for an autocatalytic reactor, the suitable reactor setup is

Answer 23

cstr followed by pfr

Question 24

ionic rxn occur in

Answer 24

solutions

Question 25

batch process is preferred over continuous process when the product

Answer 25

both a and b

Question 26

in a chemical rxn (pic) i. rate if formation of P is doubled ii. rate of formation of P is quadrupled iii. doubling the conc of Z order of rxn

Answer 26

third order

Question 27

half life period of a first order rxn is given by

Answer 27

0.693/K

Question 28

half life period of a chemical rxn is

Answer 28

the time required to reduce the conc to half its initial value

Question 29

in the gaseous phase ammonia formation rxn, the value if rquilibrium constant depends on

Answer 29

temperature

Question 30

transition state theory relates the above quantities as

Answer 30

k (infinity) T.e^E/RT

Question 31

photochemical rxn rate does not depend significantly on temperature

Answer 31

energy of reacting molecules exceeds the activation energy by absorption of light

Question 32

A cstr is to designed in which exothermic liquid phase forst order rxn is taking place. reactor has jacket in which coolant is flowing. amount of heat to be removed is

Answer 32

5/3 kW

Question 33

according to law of mass action, rate if rxn is directly proportional to the

Answer 33

molar conc of the reactants

Question 34

in a chemical rxn, ____ conserved

Answer 34

both b and c mass and atoms

Question 35

for an ideal gas mixture undergoing a reversible gaseous phase chemical rxn, the equilibrium constant is

Answer 35

increases with pressure

Question 36

in the reversible rxn of the type A + B <--> AB, in general,

Answer 36

the combination rxn will be exothermic, while the dissociation rxn will be endothermic

Question 37

a batch reactor is

Answer 37

suitable for liquid phase rxns involving small production rate

Question 38

for a first order rxn carried out in a pfr, the space time is

Answer 38

1/K ln Co/C

Question 39

for an isothermal second krder aqueous rxn, the ratio of the tine required for 90% conversion to the time required for 45% conversion is

Answer 39

11

Question 40

a chemical rxn is of zero order, when the rxn rate is

Answer 40

none of these

Question 41

second order consecutive irreversi rxn were carried out in a constant volume isothermal batch reactor with different inital feed compositions. what is the ratio of two rate constant

Answer 41

1/4

Question 42

wrong statement (enzymes)

Answer 42

enzymes help in increasing the activation energy of the rxn

Question 43

there is no correspondence between stoichiometry and the rate equation in case of

Answer 43

non-elementary rxn

Question 44

a spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface rxn AB. the effectiveness factor of the catalyst is reported as 7/8. which of the following is true

Answer 44

inner catalyst core of radius R/8 does not participate in rxn

Question 45

which of the following is used for the calcinationif limestone and dolomite

Answer 45

moving bed reactor

Question 46

an imbalanced chemical rxn equation is against the law of

Answer 46

conservation of mass

Question 47

for the chemical rxn PQ found that the rate of rxn doubles as the concentration of P doubled. what is the value of n for the rxn

Answer 47

1

Question 48

characteristics of an ideal plug flow reactor

Answer 48

flat velocity profile

Question 49

velocity of a rxn depends upon the

Answer 49

all abc

Question 50

threshold energy in a rxn is equal to the

Answer 50

sum of a and b activation energy and normal energy