A. Twice
B. Half
C. Equal
D. None of these
Related Mcqs:
- 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 - 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 - When the reaction is dominated by intraparticle diffusion, the apparent order of reaction (nD) as measured is related to the true order (n) as ________________?
A. nD = (n + 1)/2
B. nD = n/2
C. nD = n + 1
D. None of these - A chemical reaction occurs, when the energy of the reacting molecules is ________________ the activation energy of reaction?
A. Less than
B. Equal to
C. More than
D. Equal to or more than - 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 - 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 - 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 - Rate constant for a first order reaction does not depend upon reaction time, extent of reaction and the initial concentration of reactants; but it is a function of reaction temperature. In a chemical reaction, the time required to reduce the concentration of reactant from 100 gm moles/litre to 50 gm moles/litre is same as that required to reduce it from 2 gm moles/litre to 1 gm mole/litre in the same volume. Then the order of this reaction is ?
A. 0
B. 1
C. 2
D. 3 - 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 - At a given value of E/R (ratio of activation energy and gas constant), the ratio of the rate constants at 500°K and 400°K is 2, if Arrhenius law is used. What will be this ratio, if transition state theory is used with the same value of „E/R‟ ?
A. 1.6
B. 2
C. 2.24
D. 2.5
