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 : 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 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 ... in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & prod
Last Answer : (C) Enzymes help in increasing the activation energy of the reaction
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 : A catalyst is a substance which (a) Changes the equilibrium of a reaction so that the concentration of the product increases (b) Increases the rate of reaction and increases the equilibrium concentration of products (c) Hastens the attainment of equilibrium (d) Increases the activation energy
Last Answer : Ans:(c)
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 : 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 : 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 : 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 : 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 : 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 : Pick out the correct statement. (A) A chemical reaction accompanied by absorption of heat is called an exothermic reaction (B) A chemical reaction accompanied by evolution of heat is called an ... does not change on changing the concentration units (D) Chemical equilibrium state is dynamic in nature
Last Answer : (C) The rate constant for a first order reaction does not change on changing the concentration units
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 : Object is in equilibrium if resultant force acting on it is A. increasing B. decreasing C. zero D. becomes constant
Last Answer : zero
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 : 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
Description : 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 ... decreases. D The potential energy of the products decreases. E The rate of chemical reaction decreases.
Last Answer : A The reaction follows an alternative pathway of lower activation energy.
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 : If the rate of a chemical reaction becomes slower at a given temperature, then the (A) Initial concentration of the reactants remains constant (B) Free energy of activation is lower (C) Entropy changes (D) Free energy of activation is higher
Last Answer : (D) Free energy of activation is higher
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 : 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) 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 : Arrhenius equation K = Ae-E a / R T In some reactions, Rate of reaction is directly proportional to. Concentration of catalyst Catalyst used in Bio-Chemical reactions is called. Enzymes Reactions catalyzed by light are called as. Photo catalyzed or Photosensitised reactions
Last Answer : Define order of reaction
Description : Isoenzymes can be characterized by (A) Proteins lacking enzymatic activity that are necessary for the activation of enzymes (B) Proteolytic enzymes activated by hydrolysis (C) Enzymes with identical primary structure (D) Similar enzymes that catalyse different reaction
Description : The reason why a catalyst increases the rate of reaction is that, it (A) Decreases the energy barrier for reaction (B) Increases the activation energy (C) Decreases the molecular collision diameter (D) None of these
Last Answer : (A) Decreases the energy barrier for reaction
Description : The reaction rate almost gets doubled for 10°C rise in temperature. This is due to the fact that the (A) Increased temperature reduces the activation energy (B) Fraction of molecules having threshold energy increases (C) Collision frequency increases (D) Value of threshold energy decreases
Last Answer : (B) Fraction of molecules having threshold energy increases
Description : Adiabatic heating and Adiabatic cooling really means _________ and _________ respectively. a. raising the temp and lowering the temp b. maintaining the pressure and changing the temperature c. decreasing the volume and increasing the pressure d. lowering the temp and raising the temp
Last Answer : raising the temp and lowering the temp
Description : The P/V ratio can be improved by A. Decreasing the selling price per unit B. Increasing variable cost C. Changing the sales mix D. None of the above
Last Answer : C. Changing the sales mix
Description : Unsteady uniform flow is represented by flow through a/an (A) Long pipe at constant rate (B) Long pipe at decreasing rate (C) Expanding tube at increasing rate (D) Expanding tube at constant rate
Last Answer : (B) Long pipe at decreasing rate
Description : Steady non-uniform flow is exemplified by flow through a/an (A) Long pipe at constant rate (B) Long pipe at decreasing rate (C) Expanding tube at increasing rate (D) Expanding tube at constant rate
Last Answer : (D) Expanding tube at constant rate
Description : Unsteady non-uniform flow is represented by flow through a/an (A) Long pipe at constant rate (B) Long pipe at decreasing rate (C) Expanding tube at increasing rate (D) Expanding tube at constant rate
Last Answer : (C) Expanding tube at increasing rate
Description : An example of unsteady non uniform flow is the flow of liquid under pressure through a (A) Tapering pipe at constant flow rate (B) Tapering pipe at either decreasing or increasing flow rate (C) Long pipeline of constant diameter (D) None of these
Last Answer : (B) Tapering pipe at either decreasing or increasing flow rate
Description : Arrhenius equation represents graphically the variation between the __________ and temperature. (A) Rate of reaction (B) Frequency factor (C) Rate constant (D) Activation energy
Last Answer : (C) Rate constant
Description : Arrhenius equation shows the variation of __________ with temperature. (A) Reaction rate (B) Rate constant (C) Energy of activation (D) Frequency factor
Last Answer : (B) Rate constant
Description : A reduction in the number of producers will result in equilibrium price (a) increasing and quantity increasing ; (b) increasing and quantity decreasing ; (c) decreasing and quantity increasing ; (d) decreasing and quantity decreasing
Last Answer : (b) increasing and quantity decreasing ;
Description : A shift outward in supply curve will result in equilibrium price (a) increasing and quantity increasing ; (b) increasing and quantity decreasing ; (c) decreasing and quantity increasing ; (d) decreasing and quantity decreasing
Last Answer : (c) decreasing and quantity increasing ;
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
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 : For a spontaneous natural process at constant temperature and pressure, the free energy of the system always (A) Increases (B) Decreases (C) Remain constant (D) Increases to a maximum before decreasing
Last Answer : : Option A
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 : 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 : 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 rate constant of a chemical reaction increases by increasing the (A) Temperature (B) Pressure (C) Reactant's concentration (D) None of these
Last Answer : (A) Temperature
Description : The critical spark energy required to ignite a given mixture A. decreases with decreasing sparking voltage B. increases with decreasing sparking voltage C. increases with increasing sparking voltage D. decreases with increasing sparking voltage
Last Answer : ANSWER : D
Description : Promoter (A) Initiates a chemical reaction and is a catalyst by itself (B) Alters the position of equilibrium in a reversible reaction (C) Increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals (D) All (A), (B) and (C)
Last Answer : (C) Increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals
Description : Metabolism is carried out by a large class of proteins that decrease the activation energy required for chemical reactions inside a cell. Therefore they only facilitate reactions that would naturally occur at a much slower rate. What is the name of these proteins that speed up biochemical reactions?
Last Answer : Enzymes
Description : During inter conversion of energy from one form to other forms, total energy at any time remains– (1) constant (2) zero (3) increasing (4) decreasing
Last Answer : (1) constant Explanation: During interconversion of energy from one form to other forms, total energy at any time remains constant.
Description : During size reduction by a jaw crusher, the energy consumed decreases with the (A) Decreasing size of product at constant size of feed (B) Decreasing machine capacity (C) Increasing size of feed at constant reduction ratio (D) None of these
Last Answer : (C) Increasing size of feed at constant reduction ratio
Description : The total energy of each particle at various places in the case of perfect incompressible fluid flowing in continuous stream (A) Keeps on increasing (B) Keeps on decreasing (C) Remain constant (D) May increase/decrease
Last Answer : Answer: Option C