chemical engineering chemical reaction MCQs – Page 11

Practise multiple-choice questions from chemical engineering chemical reaction for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering chemical reaction Mcqs

201. Threshold energy in a reaction is equal to the_________________?
0

A. Neither A. nor B.

B. Activation energy

C. Normal energy of reactants

D. Sum of A. & B.

202. The following gas phase reaction is taking place in a plug flow reactor. A stoichiometric mixture of A and B at 300 K is fed to the reactor. At 1 m along the length of the reactor, the temperature is 360 K. The pressure drop is negligible and an ideal gas behaviour can be assumed. Identify the correct expression relating the concentration of A at the inlet (CA0), concentration of A at 1m (CA) and the corresponding conversion of A (X) ?
0

A. CA = 0.83 CA0 (1 X)/(1 0.33X)

B. CA = 1.2 CA0 (1 X)/(1 0.33X)

C. CA = 0.83 CA0 (1 X)/(1 0.5X)

D. CA = 1.2 CA0 (1 X)/(1 0.5X)

203. Integral method for analysing the kinetic data is used _____________________?
0

A. When the data are scattered

B. For testing specific mechanisms with simple rate expressions

C. Both A. and B.

D. None of these

204. Which of the following is a characteristic of an ideal plug flow reactor ?
0

A. Flat velocity profile

B. Axial dispersion

C. None of these

D. Uniform mixing

205. The exit age distribution curve E(t) for an ideal CSTR with the average residence time, ?, is given by__________________?
0

A. e-t/?/?

B. 1 (e-t/?/?)

C. 1 e-t/?

D. e-t/?

206. Half life period of a first order irreversible reaction A ? B is ______________________?
0

A. ln k/2

B. k/2

C. ln 0.5/k

D. ln 2/k

207. The rate of an autocatalytic reaction as shown in the bellow figure, is given by rA = k . CA . CB. In this case, the__________________?
0

A. Plot of rA Vs CA is a straight line with slope k

B. Plot of rA Vs CA is a hyperbola

C. Rate of disappearance of reactant A is maximum, where CA = CB

D. Both B & C

208. In case of the irreversible unimolecular type, first order reaction, the fractional conversion at any time for constant volume system as compared to variable volume system is___________________?
0

A. Same

B. More

C. Less

D. Either A. or B., depends on other factors

209. A rise in temperature ______________________?
0

A. Does not affect photo-chemical reaction rates

B. All A., B. and C.

C. Normally tends to increase the reaction rate

D. Does not affect a catalysed reaction

210. For a tubular reactor with space time ? and residence time ?, the following statement holds good ?
0

A. ? and ? are always equal

B. ? = ?, for an isothermic tubular reactor in which the density of the process fluid is constant

C. ? = ?, for a non-isothermal reactor

D. ? = ?, when the fluid density changes in the reactor

211. For the reversible reaction A ? 2B, if the equilibrium constant K is 0.05 mole/litre; starting from initially 2 moles of A and zero moles of B, how many moles will be formed at equilibrium ?
0

A. 0.637

B. 0.338

C. 0.152

D. 0.253

212. Batch process is preferred over continuous process, when the___________________?
0

A. Sales demand of product is not steady

B. idence time

C. All A., B. & C.

D. Same equipment cannot be used for several processes of the same nature

E. Product yields and quality cannot be achieved in continuous process, because of long

213. A chemical reaction occurs, when the energy of the reacting molecules is ________________ the activation energy of reaction?
0

A. Equal to or more than

B. More than

C. Equal to

D. Less than

214. Space velocity____________________?
0

A. Is a measure of the ease of the reaction

B. Is the maximum feed rate per unit volume of reactor for a given conversion

C. Describes the extensive operating characteristics of a tubular flow reactor

D. All A., B. and C.

215. 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 ?
0

A. I, II, III

B. III, II, I

C. II, III, I

D. III, I, II

216. In a first order reaction, the time required to reduce the concentration of reactant from 1 mole/litre to 0.5 mole/litre will be ______________ that required to reduce it from 10 moles/litre to 5 moles/litre in the same volume ?
0

A. More than

B. Same as

C. Less than

D. Data insufficient; cant be predicted

217. Find a mechanism that is consistent with the rate equation and reaction given below ?
0

A. A + A ? AA; AA + B ? A2B

B. A + A ? AA; AA + B ? A2B

C. A + B ? AB; AB + A ? A2B

D. A + B ? AB; AB + A ? A2B

E. #NAME?

218. A liquid phase reaction is to be carried out under isothermal conditions. The reaction rate as a function of conversion has been determined experimentally and is shown in the figure given below. What choice of reactor or combination of reactors will require the minimum overall reactor volume, if a conversion of 0.9 is desired ?
0

A. CSTR followed by a PFR

B. PFR followed by a CSTR followed by a PFR

C. CSTR followed by a PFR followed by a CSTR

D. PFR followed by a CSTR

219. Concentration of the limiting reactant (with initial concentration of a moles/litre) after time t is (a-x). Then t for a first order reaction is given by____________________?
0

A. k. t = ln a/(a x)

B. k. t = ln a (a x)/x

C. k. t = x/a (a x)

D. k. t = ln (a x)/a

220. In a chemical reaction as shown in the bellow figure, it is observed that the (i) Rate of formation of P is doubled on doubling the concentration of X (ii) Rate of formation of P is quadrupled on doubling the concentration of Y (iii) Doubling the concentration of Z does not affect the rate of formation of P What is the order of the above chemical reaction ?
0

A. Second order

B. Third order

C. First order

D. Zeroth order

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