Pick out the correct statement. (A) In catalytic reactions, the catalyst reacts with the reactants (B) A catalyst initiates a chemical reaction (C) A catalyst lowers the activation energy of the reacting molecules (D) A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction

Pick out the correct statement.
(A) In catalytic reactions, the catalyst reacts with the reactants
(B) A catalyst initiates a chemical reaction
(C) A catalyst lowers the activation energy of the reacting molecules
(D) A catalyst cannot be recovered chemically unchanged at the end of the
chemical reaction
by

1 Answer

Answer :

(C) A catalyst lowers the activation energy of the reacting molecules
by

Related questions

A catalyst (A) Initiates a reaction (B) Lowers the activation energy of reacting molecules (C) Is capable of reacting with any one of the reactants (D) Cannot be recovered chemically unchanged at the end of a chemical reaction

Description : A catalyst (A) Initiates a reaction (B) Lowers the activation energy of reacting molecules (C) Is capable of reacting with any one of the reactants (D) Cannot be recovered chemically unchanged at the end of a chemical reaction

Last Answer : (C) Is capable of reacting with any one of the reactants

For a heterogeneous catalytic reaction (A) Free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction (B) A relatively small amount of catalyst can cause the conversion of large amount of reactants which does not mean that catalyst concentration is important (C) The catalyst does not form an intermediate complex with the reactant (D) The surface of the catalyst does not play an important role during reaction

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Last Answer : (A) Free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction

Pick out the wrong statement. (A) Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition (B) Alumina is added as a promoter to iron catalyst in ammonia synthesis reaction (C) Activation energy for a reaction is obtained from the intercept of the Arrhenius plot (D) Presence of inerts affects the equilibrium conversion of reactants in a chemical reaction

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Pick out the correct statement. (A) Reactions with high activation energies are very temperature sensitive (B) Chemical equilibrium is a static state (C) A photochemical reaction is catalysed by light (D) A chemical reaction occurs when the energy of the reacting molecule is less than the activation energy of the reaction

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Last Answer : (A) Reactions with high activation energies are very temperature sensitive (B) Chemical equilibrium is a static state

Pick out the correct statement. (A) A catalyst does not change AH of the reaction (B) A catalyst changes the equilibrium point (C) Law of mass action was suggested by Le-Chatelier (D) The difference between the energy of reactants and that of the products is the activation energy

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Pick out the wrong statement. (A) Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45°C(B) Most of the enzyme catalysed reactions involve at least two substrates (C) Enzymes help in increasing the activation energy of the reaction (D) Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & prod

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Last Answer : (C) Enzymes help in increasing the activation energy of the reaction

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

A catalyst in a chemical reaction (A) Decreases the activation energy (B) Alters the reaction mechanism (C) Increases the frequency of collisions of reacting species (D) All (A), (B) and (C)

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Pick out the wrong statement. (A) In a multistep reaction, the slowest step is the rate determining step (B) In general, the rate of a reaction becomes triple for every 10°C rise in temperature (C) Slow chemical reactions have generally high values of activation energy (D) Molecularity of a reaction cannot be zero but the order of a reaction can be zero

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A chemical reaction occurs when the energy of the reacting molecules is __________ the activation energy of the reaction. (A) Less than (B) Equal to (C) More than (D) Equal to or more than

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Last Answer : (D) Equal to or more than

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Catalytic action in a catalytic chemical reaction follows from the ability of catalyst to change the (A) Activation energy (B) Equilibrium constant (C) Heat of reaction (D) None of these

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What happens when a catalyst is added to a system at equilibrium? A The reaction follows an alternative pathway of lower activation energy. B The heat of reaction decreases. C The potential energy of the reactants decreases. D The potential energy of the products decreases. E The rate of chemical reaction decreases.

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Last Answer : A The reaction follows an alternative pathway of lower activation energy.

The difference between Threshold energy and average energy of the molecules is called activation energy. Ina chemical reaction lowers the rate of reaction the greater will be. The activation energy

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Which one of the following statements regarding a catalyst is not correct? A An enzyme is a catalyst that only binds certain substrates. B An enzyme is a protein that is a highly efficient catalyst for one or more chemical reactions in a living system. C Catalysts increase the rate of a reaction by altering the mechanism, thereby increasing the activation energy. D Catalysts do not alter the equilibrium constant for a chemical reaction.

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Burning of Gasoline initially requires heat before it burns spontaneously. Which of the following does not give a good explanation of this phenomenon?  a. the initial heat rises the enthalpy of the reactant  b. the initial heat lowers the activation of energy of the reactants  c. the enthalpy of reactants is lower than the enthalpy of products.  d. The enthalpy of the product is lower than the enthalpy of the reactant

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Photochemical reaction rate does not depend significantly on temperature, because (A) It is a reversible reaction (B) It is an exothermic reaction (C) The energy of reacting molecules exceeds the activation energy by absorption of light (D) None of these

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Rate of a chemical reaction is not influenced by the (A) Catalyst (B) Temperature (C) Reactants concentration (D) Number of molecules of reactants taking part in a reaction

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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 a reaction involving many steps is the fastest step (D) Pore volume and porosity of a catalyst is measured by Brunauer￾Emmett-Teller (BET) technique

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"The rate at which a substance reacts is proportional to its active mass and the rate of a chemical reaction is proportional to the product of active masses of the reacting substances". This is the (A) Lewis-Randall rule (B) Statement of Van't Hoff Equation (C) Le-Chatelier's principle (D) None of these

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The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy. (A) Activation (B) Potential (C) Binding (D) Threshold

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Pick out the wrong statement. (A) Lower boiling paraffins have higher octane number than higher paraffins (B) Dehydrogenation of naphthenes to aromatics is a desirable reaction in reforming process (C) The most ideal feedstock for thermal reforming is dearomatised kerosene (D) Catalyst used in catalytic reforming is platinum on silica-alumina base

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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 a second order reaction, the slope of the graph/plot between rate and (concentration) is equal to the rate constant (k) (D) Molecularity of the reaction is always a whole number greater than zero

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

Pick out the correct statement. (A) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas (B) The 'Hatta number' is important in problems involving gas absorption without chemical reaction (C) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion (D) Total reflux in case of distillation operation requires infinite number of plates for a binary system separation

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Pick out the correct statement pertaining to catalytic cracking. (A) With increase in the reactor pressure, octane number of gasoline decreases (B) With increase in the reactor temperature, gasoline yield decreases for a given conversion (C) Percentage conversion increases with increase in the catalyst to oil ratio (D) All (A), (B) and (C)

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A catalyst remains unchanged at the end of the reaction with regard to (a) Quality (b) Chemical composition (c) Physical state (d) Quantity and chemical composition

Description : A catalyst remains unchanged at the end of the reaction with regard to (a) Quality (b) Chemical composition (c) Physical state (d) Quantity and chemical composition

Last Answer : Ans:(d)

The role of a catalyst in a chemical reaction is to change the (A) Equilibrium constant (B) Activation energy (C) Final products (D) Heat of reaction

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The catalyst in a first order chemical reaction changes the (A) Equilibrium constant(B) Activation energy(C) Heat of formation of the product(D) Heat of reaction

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Last Answer : (B) Activation energy

In autocatalytic reactions, (A) One of the reactants acts as a catalyst (B) One of the products acts as a catalyst (C) Catalysts have very high selectivity (D) No catalyst is used

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Last Answer : (B) One of the products acts as a catalyst

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 reaction is practically irreversible in nature (C) The intercept of the Arrhenius plot is called the 'activation energy' (D) Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant regions

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

In a reaction, the threshold energy is equal to (where, A = activation energy N = normal energy of reactants) (A) A (B) N (C) A + N (D) A - N

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Threshold energy in a reaction is equal to the (A) Activation energy (B) Normal energy of reactants (C) Sum of (A) & (B) (D) Neither (A) nor (B)

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Last Answer : (C) Sum of (A) & (B)

The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst. (A) Increases (B) Decreases (C) Remain unaffected (D) Unpredictable from the data

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Last Answer : (C) Remain unaffected

Role of an enzyme in reactions is to/as (a) decrease activation energy (b) increase activation energy (c) inorganic catalyst (d) none of the above.

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Last Answer : (a) decrease activation energy

The minimum energy required to allow a chemical reaction to proceed is termed as the 'threshold energy '. Chemical reactions with low activation energy are: (A) Always irreversible (B) Insensitive to temperature changes (C) Mostly irreversible (D) Highly temperature sensitive

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Last Answer : (B) Insensitive to temperature changes

Pick out the wrong statement. (A) ****, *** & Vodka are prepared by the formulation of fruit juice, sugar beet & rye respectively (B) Protein catalysts are called enzymes (C) The rate of chemical reaction is independent of the concentration of reactants at high concentration of enzymes (D) Total sugar content in molasses is about 10%

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Last Answer : (D) Total sugar content in molasses is about 10%

The energy of activation of a chemical reaction: (A) Is same as heat of reaction at constant pressure (B) Is the minimum energy which the molecules must have before the reaction can take place (C) Varies as fifth power of the temperature (D) Both (B) and (C)

Description : The energy of activation of a chemical reaction: (A) Is same as heat of reaction at constant pressure (B) Is the minimum energy which the molecules must have before the reaction can take place (C) Varies as fifth power of the temperature (D) Both (B) and (C)

Last Answer : (B) Is the minimum energy which the molecules must have before the reaction can take place

If the pore diffusion controls in a catalytic reaction, the apparent activation energy Ea is equal to (A) The intrinsic activation energy E (B) (E + ED) where ED is activation due to diffusion (C) (E + ED)/2 (D) ED/2

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The rate expression for a heterogeneous catalytic reaction is given by, - rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR >> (1 + KA PA), the apparent activation energy EA is equal to (given E is the activation energy for the reaction and ΔHR and ΔHA are the activation energies of adsorption of R and A) (A) E (B) E + ΔHA (C) E + ΔHA - ΔHR ) (D) ΔHA + ΔHR

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Last Answer : (C) E + ΔHA - ΔHR )

Velocity of a chemical reaction (A) Decreases with increase in temperature (B) Increases with increase of pressure of reactants for all reactions (C) Decreases with increase of reactant concentration (D) None of these

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Last Answer : (D) None of these

Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction?(A) Ash resistance (B) Gas film and pore surface diffusion resistances for reactants (C) Surface phenomenon resistance (D) Gas film and pore surface diffusion resistances for products

Description : Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction? (A) Ash resistance (B) Gas film and pore surface diffusion resistances for reactants (C) Surface phenomenon resistance (D) Gas film and pore surface diffusion resistances for products

Last Answer : (A) Ash resistance