Pick out the wrong statement.
(A) The vessel dispersion number (D/UL) for plug flow and mixed flow
approaches zero and infinity respectively
(B) Space time in a flow reactor is a measure of its capacity and is equal to
the residence time when the density of reaction mixture is constant
(C) Mixed reactor is always smaller than the plug flow reactor for all
positive reaction orders for a particular duty
(D) In an ideal tubular flow reactor, mixing takes place in radial direction
and there is no mixing in longitudinal direction

1 Answer

Answer :

(C) Mixed reactor is always smaller than the plug flow reactor for all
positive reaction orders for a particular duty

Related questions

Description : Pick out the wrong statement. (A) For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank reactor provides higher overall selectivity(B) For an ideal ... D) Reaction rate does not decrease appreciably as the reaction proceeds in case of an autocatalytic reaction

Last Answer : (A) For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank reactor provides higher overall selectivity

Description : In an ideal tubular-flow reactor (A) There is no mixing in longitudinal direction (B) Mixing takes place in radial direction (C) There is a uniform velocity across the radius (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Description : For all positive reaction orders for a particular duty, (A) Mixed reactor is always larger than the plug-flow reactor (B) Ratio of the volume of the mixed reactor to that of the plug-flow ... (C) Reactor size is independent of the type of flow (D) Density variation during reaction affects design

Last Answer : (A) Mixed reactor is always larger than the plug-flow reactor

Description : Pick out the wrong statement. (A) The integral method of analysing kinetic data is used when the data is scattered (B) The differential method of analysing kinetic data requires more accurate ... less than one for identical feed composition, flow rate, conversion and for all positive reaction orders

Last Answer : (C) When the reaction rate is independent of temperature, the reaction is said to be of zero order

Description : The size of plug flow reactor (PFR) for all positive reaction orders and for any given duty, is __________ that of mixed reactor. (A) Greater than (B) Equal to (C) Smaller than (D) Unpredictable from the data

Last Answer : (C) Smaller than

Description : 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

Last Answer : (B) Velocity of reaction can be controlled

Description : Pick out the wrong statement: (A) Chemical reactions with high activation energy are very temperature sensitive (B) A flat velocity profile exists in a plug flow reactor (C) The residence ... D) Half life of a reaction increases with increased initial concentration for reaction orders more than one

Last Answer : (C) The residence time for all the elements of fluid in case of a P.F.R. need not be same

Description : Space time equals the mean residence time (A) When the density of the reaction mixture is constant (B) For large diameter tubular reactor (C) For narrow diameter tubular reactor (D) For CSTR

Last Answer : (A) When the density of the reaction mixture is constant

Description : Pick out the correct statement. (A) A lower temperature favours the reaction of lower activation energy (B) The dispersion number for a reactor/vessel is uL/D (C) The rate controlling step in ... step (D) Pore volume and porosity of a catalyst is measured by Brunauer￾Emmett-Teller (BET) technique

Last Answer : (A) A lower temperature favours the reaction of lower activation energy

Description : A plug-flow reactor is characterised by (A) High capacity (B) Presence of axial mixing (C) Presence of lateral mixing (D) Constant composition and temperature of reaction mixture

Last Answer : (C) Presence of lateral mixing

Description : Mean residence time is equal to the space time, when (A) The feed rate is measured at temperature and pressure in the reactor (B) The temperature, pressure and the density of reaction mixture remains constant throughout ... no change in number of moles in gaseous reaction (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Description : With increase in the order of reaction (for all positive reaction orders), the ratio of the volume of mixed reactor to the volume of plug flow reactor (for identical feed composition, flow rate and conversion). (A) Increases (B) Decreases (C) Remain same (D) Increases linearly

Last Answer : (A) Increases

Description : Pick out the wrong statement. (A) 'Hold back' is defined as the fraction of material that stays longer than the mean residence time (B) Study of non-ideal flow reactor is done experimentally ... final stages of reaction (D) A batch reactor cannot be used to study the kinetics of catalytic reaction

Last Answer : (D) A batch reactor cannot be used to study the kinetics of catalytic reaction

Description : The use of space time is preferred over the mean residence time in the design of a/an (A) Batch reactor (B) Ideal tubular-flow reactor (C) Slurry reactor (D) CSTR

Last Answer : (B) Ideal tubular-flow reactor

Description : A backmix reactor (A) Is same as plug-flow reactor (B) Is same as ideal stirred tank reactor (C) Employs mixing in axial direction only (D) Is most suitable for gas phase reaction

Last Answer : (B) Is same as ideal stirred tank reactor

Description : Pick out the wrong statement. (A) A particular chemical reaction is more temperature sensitive at low temperatures (B) A very high value of equilibrium constant, K (K >> 1) indicates that the ... ) Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant regions

Last Answer : (C) The intercept of the Arrhenius plot is called the 'activation energy

Description : Space time in flow reactor is (A) Usually equal to the residence time (B) The reciprocal of the space velocity (C) A measure of its capacity (D) Both (A) and (B)

Last Answer : (D) Both (A) and (B)

Description : For a packed bed reactor; the presence of a long tail in the residence time distribution curve is an indication of: (A) Ideal plug flow (B) Bypass (C) Dead zone (D) Channelling

Last Answer : (C) Dead zone

Description : A second order liquid phase reaction, A → B, is carried out in a mixed flow reactor operated in semi batch mode (no exit stream). The reactant A at concentration CAF is fed to the reactor at a volumetric flow rate of F. The volume ... 2V (C) d(VCA )/dt = -FCA - kCA 2V (D) d(VCA )/dt = FCAF - kCA 2V

Last Answer : (D) d(VCA )/dt = FCAF - kCA 2V

Description : An isothermal irreversible reaction is being carried out in an ideal tubular flow reactor. The conversion in this case will __________ with decrease in space time. (A) Increase (B) Increase exponentially (C) Decrease (D) Remain unchanged

Last Answer : (C) Decrease

Description : Space velocity (A) Describes the extensive operating characteristics of a tubular flow reactor (B) Is the maximum feed rate per unit volume of reactor for a given conversion (C) Is a measure of the ease of the reaction (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Description : For series reaction, the relative yield (A) Is always greater for plug-flow reactor than for the single CSTR of the same volume (B) Statement in (A) is wrong (C) Decreases with increasing conversion (D) Both (A) and (C) hold good

Last Answer : (D) Both (A) and (C) hold good

Description : When the density of the reaction mixture is constant in a chemical reaction, the ratio of the mean residence time to space time is (A) > 1 (B) < 1 (C) 1 (D) 0

Last Answer : (C) 1

Description : For the same residence time, which one will give the maximum conversion? (A) Single stirred tank (v = 5 litres) (B) Two stirred tank (each of 2.5 litres) in series (C) Stirred tank followed by tubular flow reactor (each of 2.5 litres) (D) Single tubular flow reactor (v = 5 litres)

Last Answer : (D) Single tubular flow reactor (v = 5 litres)

Description : In an ideal mixed reactor (at steady state), the (A) Space time is equivalent to holding time for constant density systems (B) Composition throughout the reactor remains same (C) Exit stream has the same composition as the fluid within the reactor (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Description : An isothermal aqueous phase reversible reaction, P ⇌ R, is to be carried out in a mixed flow reactor. The reaction rate in k.mole/m3 .h is given by, r = 0.5CP - 0.125CR. A stream containing only P enters the reactor. The ... (in hours) for 40% conversion of P is (A) 0.80 (B) 1.33 (C) 1.60 (D) 2.67

Last Answer : (C) 1.60

Description : . A batch reactor is characterised by (A) Constant residence time (B) Variation in extent of reaction and properties of the reaction mixture with time (C) Variation in reactor volume (D) Very low conversion

Last Answer : (B) Variation in extent of reaction and properties of the reaction mixture with time

Description : Pick out the wrong statement. (A) In a batch reactor, which is exclusively used for liquid phase reactions; temperature pressure and composition may vary with time (B) In a semi-batch reactor, ... system (D) In a continuous flow reactor, both the reactants and the products flow out continuously

Last Answer : (C) In a continuous flow reactor, uniform concentration cannot be maintained throughout the vessel even in a well agitated system

Description : Pick out the wrong statement. (A) Activity co-efficient is dimensionless. (B) In case of an ideal gas, the fugacity is equal to its pressure. (C) In a mixture of ideal gases, the fugacity of ... equal to the partial pressure of the component. (D) The fugacity co-efficient is zero for an ideal gas

Last Answer : (D) The fugacity co-efficient is zero for an ideal gas

Description : The space time is equivalent to the holding time in a steady state mixed reactor for (A) Non-isothermal gas reaction (B) Variable fluid density systems (C) Constant fluid density systems (D) Gas reactions with changing number of moles

Last Answer : (C) Constant fluid density systems

Description : The Prandtl mixing length is (A) Zero at the pipe wall and is a universal constant (B) Independent of radial distance from the pipe axis (C) Independent of the shear stress (D) Useful for computing laminar flow problems

Last Answer : (D) Useful for computing laminar flow problems

Description : Pick out the wrong statement. (A) Visible radiation provides the necessary activation energy in photochemical reactions (B) The order and molecularity of a complex reaction may not be the same (C) For ... rate constant (k) (D) Molecularity of the reaction is always a whole number greater than zero

Last Answer : (B) The order and molecularity of a complex reaction may not be the same

Description : The vessel dispersion number (D/μL) for plug flow is (A) 0 (B) 500 (C) 750 (D) ∞

Last Answer : (A) 0

Description : Pick out the wrong statement. (A) The form drag is dependent upon the occurrence of a wake (B) The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent ... of viscosity (D) Existence of the boundary layer in fluid flow is because of viscosity of the fluid

Last Answer : (C) An ideal fluid is the one, which has negligible surface tension and obeys the Newton's law of viscosity

Description : In a semi-batch reactor (A) Velocity of reaction can be controlled (B) Maximum conversion can be controlled (C) Both the reactants flow counter-currently (D) Residence time is constant

Last Answer : (A) Velocity of reaction can be controlled

Description : What is the dispersion number for a plug flow reactor? (A) 0 (B) ∞ (C) 1 (D) -1

Last Answer : (A) 0

Description : Pick out the wrong statement about a streamline. (A) It is always parallel to the main direction of the fluid flow (B) It is a line across which there is no flow and it is ... any two streamlines can be considered to be in isolation and the streamline spacing varies inversely as the velocity

Last Answer : (A) It is always parallel to the main direction of the fluid flow

Description : Pick out the wrong statement. (A) Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient (B) In a shell and tube heat exchanger ... surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube

Last Answer : (C) S.I. unit of fouling factor is Watt/m2 .°K

Description : Pick out the wrong statement. (A) Fluid movement under the influence of buoyant forces resulting from change in density takes place in case of natural convection (B) The ratio NNu /NRe . Npr is ... convection to that by conduction (D) The Colburn jH factor for heat transfer is given by Nst Npr

Last Answer : (D) The Colburn jH factor for heat transfer is given by Nst Npr

Description : Kinetics of a catalytic reaction can be best studied on a/an __________ reactor. (A) Mixed (B) Integral (plug flow) (C) Differential (flow) (D) Either (A), (B) and (C)

Last Answer : (D) Either (A), (B) and (C)

Description : Kinetics of a solid catalysed reaction can best be studied in a __________ reactor. (A) Batch (B) Plug-flow (C) Mixed (D) None of these

Last Answer : (C) Mixed

Description : Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature. (A) Infinity (B) Minus infinity (C) Zero (D) None of these

Last Answer : (B) Minus infinity

Description : Pick out the wrong statement. (A) In a first order reaction, A → products; the reaction becomes slower as it proceeds, because the concentration of A decreases and the rate is proportional to the concentration ... irreversible reaction, A + B → 2C is k.CA .CB , then the reaction is always elementary

Last Answer : (C) According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases

Description : Which of the following fixes the volume of a batch reactor for a particular conversion and production rate? (A) Operating conditions (e.g. pressure and temperature) (B) Rate constant (C) Density of mixture (D) None of these

Last Answer : (C) Density of mixture

Description : Fluid flow in a real packed bed can be approximated as __________ model. (A) Plug flow (B) Dispersion (C) Mixed flow (D) Tank in series

Last Answer : (B) Dispersion

Description : As the temperature is lowered towards the absolute zero, the value of ∂(∆F)/∂T, then approaches (A) Unity (B) Zero (C) That of the heat of reaction (D) Infinity

Last Answer : B) Zero

Description : The advantages of electrometric bearings are a) Permits movement of the structure in all directions b) Serves as a shock absorber due to anti-vibration properties of elestomeric c) better dispersion of longitudinal forces to the approaches d) All of the above*

Last Answer : d) All of the above*

Description : Hydrogenation of oil takes place in a/an __________ reactor. (A) Autothermal (B) Trickle bed (C) Plug flow (D) None of these

Last Answer : (B) Trickle bed