Chemical Reaction Engineering Exam Questions - Set 22 - ObjectiveBooks

Chemical Reaction Engineering Exam Questions - Set 22

Practice Test: Question Set - 22

1. The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is
    (A) Backmix reactor
    (B) Plug flow reactor
    (C) Series of CSTR
    (D) PFR in series

2. The synthesis of proteins and metabolism in biological objects occur in the presence of biocatalyst called
    (A) A ferment or an enzyme
    (B) Haemoglobin
    (C) Fungi
    (D) None of these

3. Pure ethanol vapor is fed to a reactor packed with alumina catalyst, at the rate of 100 kmole / hr. The reactor products comprise: ethylene: 95 kmole / hr, water vapor: 97.5 k mole / hr and diethyl ether: 2.5 kmole/hr. The reactions occurring can be represented by:

    C2H5OH → C2H4 + H2O
    2C2H5OH → C2H5 - O - C2H5 + H2O

The percent conversion of ethanol in the reactor is

    (A) 100
    (B) 97.5
    (C) 95
    (D) 2.5

4. If the time required for half change is inversely proportional to the square of initial concentration and the velocity depends on the units in which the concentration term is expressed, then the order of reaction is
    (A) 0
    (B) 1
    (C) 2
    (D) 3

5. 'If the catalyst pore size is small in comparison with the mean free path, collisions with the pore wall controls the process'. The diffusivity under this condition is called 'Knudsen diffusivity', which is affected by the
    (A) Pressure
    (B) Temperature
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

6. In case of a/an __________ chemical reaction, conversion increases with the rise in temperature.
    (A) Reversible exothermic
    (B) Irreversible exothermic
    (C) Irreversible endothermic
    (D) Reversible endothermic

7. 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

8. Transition state theory gives the rate constant as
    (A) K α e-E/RT
    (B) K α eE/RT
    (C) K α T . e-E/RT
    (D) K α √T . e-E/RT

9. 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)

10. What is the dispersion number for a plug flow reactor?
    (A) 0
    (C) 1
    (D) -1

11. Transition state theory relates the above quantities as
    (A) k  e-E/RT
    (B) k  T.eE/RT
    (C) k  √T
    (D) k  T1.5

12. The rate equation for the reaction represented by as shown in the bellow figure, is given by - rx = K1 . Cx/(1 + K2 Cx). At high value of Cx (i.e.., K2Cx > > 1), the order of the reaction and the rate constant are respectively
    (A) Zero order & K1/K2
    (B) Zero order & K1
    (C) First order & K1
    (D) First order & K1/K2

13. The dimensions of rate constant for reaction 3A → B are (l/gm mole)/min. Therefore the reaction order is
    (A) 0
    (B) 1
    (C) 2
    (D) 3

14. For a __________ order chemical reaction as shown in the bellow figure, the fractional conversion of reactant 'A' is proportional to time.
    (A) Zero
    (B) First
    (C) Second
    (D) Third

15. Second order consecutive irreversible reaction as shown in the bellow figure, 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

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