chemical engineering chemical reaction Mcqs
101. The space time is equivalent to the holding time in a steady state mixed reactor for_____________________?
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A. Gas reactions with changing number of moles

B. Non-isothermal gas reaction

C. Variable fluid density systems

D. Constant fluid density systems
102. The rate of a gas phase reaction is given by K . CA . CB. If the volume of the reaction vessel is reduced to l/4th of its initial volume, then the reaction rate compared to the original rate will be _______________ times?
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A. 8

B. 2

C. 4

D. 16
103. Inversion of cane sugar is an example of ______________________?
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A. Unimolecular reaction with second order

B. Bimolecular reaction with first order

C. Unimolecular reaction with first order

D. Bimolecular reaction with second order

104. Vegetable oils are hydrogenated in a _______________ reactor?
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A. Plug flow

B. Homogeneous catalytic

C. None of these

D. Slurry
105. Knudsen diffusion is directly proportional to _____________________?
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A. ?T

B. T2

C. T

D. 1/?T

106. If ?G (free energy change) for a chemical reaction is very large and negative, then the reaction is_______________________?
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A. Just feasible

B. Very much feasible

C. Unpredictable as ?G is no measure of feasibility of a reaction

D. Not feasible

107. A non-catalytic chemical reaction of the type as shown in the bellow figure is called a _____________ reaction?
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A. Series-parallel

B. None of these

C. Series

D. Parallel

108. Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure ?
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A. None of these

B. Freundlich adsorption isotherm

C. Langmuir adsorption isotherm

D. Adsorption isobar
109. A batch reactor is characterised by ____________________?
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A. Variation in reactor volume

B. Constant residence time

C. Very low conversion

D. Variation in extent of reaction and properties of the reaction mixture with time
110. In autocatalytic reactions ?
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A. One of the products acts as a catalyst

B. Catalysts have very high selectivity

C. No catalyst is used

D. One of the reactants acts as a catalyst

111. Limiting reactant in a chemical reaction decides the____________________?
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A. Reaction speed

B. Equilibrium constant

C. Rate constant

D. Conversion
112. With increase in the space time of an irreversible isothermal reaction being carried out in a P.F. reactor, the conversion will________________?
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A. Increase

B. Data in insufficient; cant be predicted

C. Remain same

D. Decrease

113. The catalytic converter for conversion of SO2 to SO3 by contact process should have a feed with SO2 content between___________________?
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A. 2-5 %

B. 7-10 %

C. 12-15 %

D. 20-25 %

114. _____________ gas is normally employed in B.E.T. method of finding out the surface area of catalyst?
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A. N2

B. CO2

C. He

D. H2

115. Effectiveness factor of a catalyst pellet is a measure of the _________________ resistance?
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A. Chemical reaction

B. None of these

C. Pore diffusion

D. Gas film

116. What is the maximum possible value of FR(mole/sec.) ?
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A. 2-Jan

B. 2/3

C. 2

D. 3-Jan

117. An irreversible first order reaction is being carried out in a CSTR and PFR of same volume. The liquid flow rates are same. The relative conversion will__________________?
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A. Be more in CSTR than in PFR

B. Be more in PFR than in CSTR

C. Be same in both cases

D. Depend on the temperature

118. The rate constant of a reaction depends on the __________________?
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A. Temperature of the system

B. Time of reaction

C. Extent of reaction

D. Initial concentration of reactants

119. ________________ resistance is not involved in the combustion of a carbon particle?
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A. Chemical reaction

B. Gas film

C. None of these

D. Ash
120. In Langmuir treatment of adsorption,_________________?
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A. the rate of adsorption per site</strong>

B. Whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect

C. raction between the adsorbed molecule

D. Whole surface of the catalyst does not have the same activity for adsorption and there is

E. All the adsorption does not take place by the same mechanism

F. Extent of adsorption is more than one complete monomolecular layer on the surface

121. A first order irreversible reaction, A ? B is carried out separately in a constant volume as well as in a variable volume reactor for a particular period. It signifies that _____________ in the two reactors?
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A. Both conversion as well as concentration are same

B. Conversion in both will be the same but concentrations will be different

C. Both the conversion as well as concentrations will be different

D. None of these

122. Which of the following does not produce a change in the value of rate constant of a reaction ?
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A. Temperature

B. None of these

C. Concentration and catalyst

D. Pressure

123. The catalyst in a first order chemical reaction changes the_________________?
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A. Equilibrium constant

B. Heat of formation of the product

C. Heat of reaction

D. Activation energy
124. Brunauer, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates is not used to derive BET equation ?
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A. Langmuirs assumption applies to every adsorbed layer

B. None of these

C. The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer

D. There is no dynamic equilibrium between successive layer

E. cept the first one) is involved in each of the evaporation process

125. A pulse tracer is introduced in an ideal CSTR (with a mean residence time I) at time, t = 0. The time taken for the exit concentration of the tracer to reach half of its initial value will be__________________?
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A. 2?

B. 0.5?

C. ?/0.693

D. 0.693?

126. The use of space time is preferred over the mean residence time in the design of a/an____________________?
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A. Slurry reactor

B. CSTR

C. Batch reactor

D. Ideal tubular-flow reactor
127. The reaction rate constants at two different temperatures T1 and T2 are related by _________________?
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A. exp (k2/k1) = (E/R) (1/T2 1/T1)

B. ln (k2/k1) = (E/R) (1/T2 1/T1)

C. exp (k2/k1) = (E/R) (1/T1 1/T2)

D. ln (k2/k1) = (E/R) (1/T1 1/T2)
128. B.E.T. method of finding out surface area of a catalyst, uses the extension of _________________ isotherm?
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A. Tempkin

B. Langmuir

C. None of these

D. Freundlich

129. Higher free energy of activation of a chemical reaction (at a given temperature) implies ____________________?
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A. Slower rate of reaction

B. Higher rate of reaction

C. Higher equilibrium conversion

D. Both B. and C.

130. A catalyst inhibitor____________________?
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A. May be useful for suppressing undesirable side reactions

B. Lessens its selectivity

C. Is added in small quantity during the catalyst manufacture itself

D. All A., B. and C.
131. The conversion for a second order, irreversible reaction (constant volume) as shown in the bellow figure, in batch mode is given by______________?
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A. 1/(1 + k2 . CA0 . t)

B. (k2 . CA0 . t)2/ (1 + k2 . CA0 . t)

C. (k2 . CA0 . t)/ (1 + k2 . CA0 . t)

D. (k2 . CA0 . t)/ (1 + k2 . CA0 . t)2

132. The effectiveness factor for large value of Thiele modulus [L?(K/D1)] of a solid catalysed first order reaction is equal to (where, L = length of the reactor, cm, D1 = diffusion co-efficient, cm2/second) ?
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A. 1/[L?(K/D1)]

B. ?

C. 1

D. L ?(K/D1)

133. For the liquid phase parallel reactions__________________?
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A. High temperature in a PFR

B. Low temperature in a CSTR

C. Low temperature in a PFR

D. rR = K1.CA2; E1 = 80 KJ/mole

E. desired product is R. A higher selectivity of R will be achieved, if the reaction is conducted

F. rs = K1.CA ; E2 = 120 KJ/mole

134. Volume change for unimolecular type first order reaction as shown in the bellow figure, increases _____________ with time?
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A. Linearly

B. Exponentially

C. Logarithmically

D. Parabolically

135. For a first order isothermal chemical reaction in a porous catalyst, the effectiveness factor is 0.3. The effectiveness factor will increase if the____________________?
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A. Catalyst size is increased or the catalyst diffusivity is reduced

B. Catalyst size is reduced or the catalyst diffusivity is increased

C. Catalyst size is reduced or the catalyst diffusivity is reduced

D. Catalyst size is increased or the catalyst diffusivity is increased

136. The reaction A ? B is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m3is fed to the reactor at the rate of 0.01 m3 /s and at a temperature of 500 K. If the exit conversion is 20%, then the exit temperature (in k) is (Data: Heat of reaction at 298 K = 50000 kJ/ kmole of A reacted Heat capacities CPA = CPB = 100kJ/kmole. K (may be assumed to be independent of temperature)) ?
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A. 500

B. 400

C. 1000

D. 600
137. With increase in temperature, the rate constant obeying Arrhenius equation____________________?
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A. Can either increase or decrease; depends on the frequency factor

B. Decreases

C. Increases

D. Decreases exponentially
138. Which of the following is the optimum operating condition for an exothermic reversible reaction taking place in a plug-flow reactor ?
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A. None of these

B. Very low temperature should be used throughout the reaction

C. Temperature should be high in the beginning and decreased towards the end of the reaction

D. Very high temperature should be used throughout the reaction

139. Arrhenius equation represents graphically the variation between the ______________ and temperature?
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A. Frequency factor

B. Rate of reaction

C. Rate constant

D. Activation energy

140. The preferred reacting system for oxidation of o-xylene to phthalic anhydride is _____________________?
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A. Multistage multitubular reactor with interstage cooling

B. Jacketed liquid phase CSTR

C. Multitubular reactor with cooling

D. Jacketed steam heated multitubular reactor

141. If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the ________________ diffusion?
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A. Ash layer

B. Film

C. Pore

D. None of these

142. For the non catalytic reaction 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?
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A. Diffusion through ash layer

B. Chemical reaction

C. Film diffusion

D. Either A., B. or C.

143. In a zero order reaction, reactants concentration does not change with time and the_________________?
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A. Time for completion of the reaction is independent of the initial concentration

B. Reaction rate is trebled when the initial concentration is trebled

C. Time for half change is half the time taken for completion of the reaction

D. Time for half change is independent of the initial concentration

144. The first order gas phase reaction as shown in the bellow figure is conducted isothermally in batch mode. The rate of change of conversion with time is given by________________?
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A. dXA/dt = k1 (1 XA)2 (1 + 2XA)

B. dXA/dt = k1 (1 XA)/(1 + XA)

C. dXA/dt = k1 (1 XA)

D. dXA/dt = k1 (1 XA) (1 + 0.5XA)

145. Given, 3H2 + CO = CH4 + H2O, KP = 101.84 and, 4H2 + CO2 = CH4 + 2H2O, KP = 101.17 the KP for the reaction CO + H2O = CO2 + H2 is __________________?
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A. 103.01

B. 10-3.01

C. 100.67

D. 10-0.67

146. Which of the following is used for calcination of limestone and dolomite in industrial practice?
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A. Moving bed reactor

B. None of these

C. Fixed bed reactor

D. Fluidised bed reactor

147. With an increase in pressure in gaseous phase chemical reactions, the fractional conversion ______________ when the number of moles decreases?
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A. Unpredictable from the data

B. Remain unaffected

C. Increases

D. Decreases

148. 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 __________________?
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A. 9210K

B. 8987K

C. 8764K

D. 8621K

149. Catalyst is a substance, which ________________ chemical reaction?
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A. Alters the value of equilibrium constant in a reversible

B. Decreases the speed of a

C. Can either increase or decrease the speed of a

D. Increases the speed of a

150. In an ideal P.F.R. at steady state conditions ___________________?
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A. There is no lateral mixing of fluid

B. There may be diffusion along the flow path

C. The conversion of the reactant varies from point to point along a flow path

D. The composition of reactants remains constant along a flow path