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

1 Answer

Answer :

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

Related questions

Description : 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 ... increasing the activation energy. D Catalysts do not alter the equilibrium constant for a chemical reaction.

Last Answer : C Catalysts increase the rate of a reaction by altering the mechanism, thereby increasing the activation energy.

Description : 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 ... occurs when the energy of the reacting molecule is less than the activation energy of the reaction

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

Description : 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 ... Arrhenius plot (D) Presence of inerts affects the equilibrium conversion of reactants in a chemical reaction

Last Answer : (C) Activation energy for a reaction is obtained from the intercept of the Arrhenius plot

Description : 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 ... molecules (D) A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction

Last Answer : (C) A catalyst lowers the activation energy of the reacting molecules

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 : Enzymes increases the rate of reactions by (A) Increasing the free energy of activation (B) Decreasing the energy of activation (C) Changing the equilibrium constant of the reaction (D) Increasing the free energy change of the reaction

Last Answer : Answer : B

Description : Enzymes increase the rates of reactions by (A) Increasing the free energy of activation (B) Decreasing the energy of activation (C) Changing the equilibrium constant of the reaction (D) Increasing the free energy change of the reaction

Last Answer : Answer : B

Description : Enzymes accelerate the rate of reactions by (A) Increasing the equilibrium constant of reactions (B) Increasing the energy of activation (C) Decreasing the energy of activation (D) Decreasing the free energy change of the reaction

Last Answer : Answer : C

Description : 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 ... energy (D) Molecularity of a reaction cannot be zero but the order of a reaction can be zero

Last Answer : (B) In general, the rate of a reaction becomes triple for every 10°C rise in temperature

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 : 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

Last Answer : (A) Activation energy

Description : Identify the INCORRECT statement below regarding chemical equilibrium. A All chemical reactions are, in principle, reversible. B Equilibrium is achieved when the forward reaction rate equals the ... equilibrium constant. E Equilibrium is achieved when reactant and product concentrations are equal.

Last Answer : E Equilibrium is achieved when reactant and product concentrations are equal.

Description : Isozymes or iso enzymes are those enzyme which A- have same structural forms B- have different structural forms but identical catalytic properties C- catalyses oxidation reactions D- none of these

Last Answer : have different structural forms but identical catalytic properties

Description : The catalytic activity of enzymes is due to their capacity to lower the __________ energy. (A) Activation (B) Potential (C) Kinetic (D) None of these

Last Answer : (A) Activation

Description : The rate of most enzyme catalysed reactions changes with pH. As the pH increases, this rate (A) reaches a minimum, then increases (B) reaches a maximum, then decreases (C) increases (D) decreases

Last Answer : Answer : B

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 : Fibrinolytic therapy is based on activation of plasminogen, the inactive proteolytic enzyme of plasma that binds to fibrin during the formation of thrombosis. Activation of plasminogen to plasmin results ... TPA all exceed 30 minutes d. Streptokinase is significantly cheaper than urokinase or TPA

Last Answer : Answer: a, b, d Streptokinase is a bacterial protein produced by group C b-hemolytic streptococci. It is therefore antigenic in humans and can be associated with allergic reaction in ... one agent over the other. Streptokinase however, is markedly less expensive than either urokinase or TPA

Description : 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 ... R and A) (A) E (B) E + ΔHA (C) E + ΔHA - ΔHR ) (D) ΔHA + ΔHR

Last Answer : (C) E + ΔHA - ΔHR )

Description : In an interphase heat transfer process, the equilibrium state corresponds to equality of temperature in the two phases, while the condition for equilibrium in an interphase mass transfer process is ... B) Chemical potentials (C) Activity co-efficients (D) Mass transfer co-efficients

Last Answer : (A) Concentrations

Description : The catalytic efficiency of two different enzymes can be compared by the (a) formation of the product (b) pH of optimum value (c) Km value (d) molecular size of the enzyme.

Last Answer : (c) Km value

Description : Trichloroacetic acid, a strong acid, has been used by dentists for chemical cautery of hypertrophic tissue and aphthous ulcers; its mechanism of action is, BOUCHERS P 194 A. Thermodynamic ... Activation of tissue enzymes C. Osmotic pressure D. Protein precipitation (PPT) E. Neutralization

Last Answer : D. Protein precipitation (PPT)

Description : The catalytic power of enzymes is due to (a) the presence of amino acids in their structures (b) their high molecular weight (c) their ability to lower the activation energy of the reaction (d) their limited solubility in water and other solvents

Last Answer : Ans:(c)

Description : Thermodynamic equilibrium constant in a system is affected by (A) Inerts (B) Pressure (C) Temperature (D) All (A), (B) & (C)

Last Answer : (C) Temperature

Description : Pick out the correct statement. (A) A catalyst speeds up the forward reaction but slows shown the reverse reaction (B) Addition of catalyst changes the equilibrium constant (C) Pressure changes do not change the equilibrium concentrations (D) The composition of equilibrium is changed by catalyst

Last Answer : (C) Pressure changes do not change the equilibrium concentrations

Description : Pick out the wrong statement. (A) Alkylation produces a larger iso-paraffin (having higher octane number) from the reaction of an olefin with smaller iso-paraffin (B) Catalytic alkylation processes use HF ... (> 1000°C) (D) Gasoline having an octane number of 90 can be produced by alkylation process

Last Answer : (C) All the alkylation processes use very high temperature (> 1000°C)

Description : The free energy change, AG (A) Is directly proportional to the standard free energy change, AG (B) Is equal to zero at equilibrium (C) Can only be calculated when the reactants and products are present at 1mol/1 concentrations (D) Is equal to –RT in keq

Last Answer : B

Description : An enzyme promotes a chemical reaction by (A) Lowering the energy of activation (B) Causing the release of heat which acts as a primer (C) Increasing molecular motion (D) Changing the free energy difference between substrate and product

Last Answer : Answer : A

Description : 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

Last Answer : (A) A catalyst does not change AH of the reaction

Description : Pick out the wrong statement. (A) Exit age description function (E) and internal age distribution function (I) are related as, E = -(dI/dθ) (B) Chemisorption studies are useful in the ... energy (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products

Last Answer : (D) A catalyst increases the potential energy barrier over which the reactants must pass to form products

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 : Pick out the wrong statement (A) Co-current absorbers are usually used, when the gas to be dissolved in the liquid is a pure substance (B) In case of gas absorption, HETP is ... reaction (D) In actual practice, absorption is an endothermic process, while stripping is an exothermic process

Last Answer : (D) In actual practice, absorption is an endothermic process, while stripping is an exothermic process

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

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

Description : Higher free energy of activation of a chemical reaction (at a given temperature) implies (A) Slower rate of reaction (B) Higher rate of reaction (C) Higher equilibrium conversion (D) Both (B) and (C)

Last Answer : (A) Slower rate of reaction

Description : Which of the following statements about enzymes is wrong? (a) Enzymes are denatured at high temperatures. (b) Enzymes are mostly proteins but some are lipids also. (c) Enzymes are highly specific. (d) Enzymes require optimum pH and temperature for maximum activity

Last Answer : (b) Enzymes are mostly proteins but some are lipids also.

Description : 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

Last Answer : (B) Insensitive to temperature changes

Description : Enzymes (a protein) are catalysts found in organisms. Its efficiency of catalysing a reaction is due to its capacity to lower the activation energy of the reaction. The enzyme ptyalin used for food digestion is present in (A) Blood (B) Saliva (C) Intestine (D) Gland

Last Answer : (B) Saliva

Description : Isozymes or iso enzymes are those enzyme which A- have same structural forms B- have different structural forms but identical catalytic properties C- catalyses oxidation reactions D- none of these

Last Answer : have different structural forms but identical catalytic properties

Description : Organic molecules that increase the rate of metabolic reactions with themselveschangingareknown as A- coenzymes B- enzymes C- substrates D- .reactants

Last Answer : enzymes

Description : Template/lock and key theory of enzyme action is supported by (A) Enzymes speed up reaction (B) Enzymes occur in living beings and speed up certain reactions (C) Enzymes determine the direction of reaction (D) Compounds similar to substrate inhibit enzyme activity

Last Answer : Answer : D

Description : Pick out the wrong statement. (A) Biological oxygen demand (B.O.D.) value of a sewerage sample is always lower than its chemical oxygen demand (C.O.D.) value (B) Environmental pollution by ... in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere

Last Answer : (D) The characteristic of a green house body is that it allows the long wavelength incoming solar radiation to come in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere

Description : The reaction catalysed by phosphofructokinase (A) Is activated by high concentrations of ATP and citrate (B) Uses fruitose-1-phosphate as substrate (C) Is the rate-limiting reaction of the glycolytic pathway (D) Is inhibited by fructose 2, 6-bisphosphate

Last Answer : C

Description : Enzymes activity is controlled by (A) pH of the solution (B) Temperature (C) Concentration of the enzyme (D) Concentration of the substrate (E) All of these

Last Answer : Answer : C

Description : Pick out the wrong statement. (A) Trouton's ratio of non-polar liquids is calculated using Kistyakowsky equation (B) Thermal efficiency of a Carnot engine is always less than 1 (C) An equation relating pressure, volume and temperature of a gas is called ideal gas equation (D) None of these

Last Answer : (C) An equation relating pressure, volume and temperature of a gas is called ideal gas equation

Description : Pick out the wrong statement. (A) A catalyst does not alter the final position of equilibrium in a reversible reaction (B) A catalyst initiates a reaction (C) A catalyst is specific in reaction (D) A catalyst remains unchanged in chemical composition at the end the reaction

Last Answer : (B) A catalyst initiates a reaction

Description : 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

Last Answer : (B) Activation energy

Description : 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

Last Answer : (B) Activation energy

Description : PH is the negative logarithm of the hydrogen Ion Concentration express4ed in moles/liter of aqueous solution. PH of buffer solution is calculated by. Henderson's equation Name the best ... Chemical kinetics deals with study of. Rates and mechanisms of chemical and Biochemical reactions

Last Answer : What does Thermodynamics helps in predicting ?

Description : Which one of the following statements is not correct? A Since voltage depends on concentrations, using standard conditions makes it easier to compare different electrochemical reactions. B We have ... half-reactions are determined by combining the relevant half-cell with a standardised half-cell.

Last Answer : C The direction of a redox reaction can only be determined experimentally. 

Description : Which of the following will favour the reverse reaction in a chemical equilibrium reaction? (A) Increasing the concentration of one of the reactants (B) Increasing the concentration of one or more of the products (C) Removal of at least one of the products at regular interval (D) None of these

Last Answer : (B) Increasing the concentration of one or more of the products