The catalytic activity of enzymes is due to their capacity to lower the ______________ energy?

Related Mcqs:

1. 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

2. 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

3. 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

4. Overall rate of reaction in a heterogeneous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually ________________ the concentration of catalyst, if it does not entail a chain mechanism?

   A. Proportional to
   B. Independent of
   C. Inversely proportional to
   D. Proportional to the square of

5. 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

6. 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

7. 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

8. 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

9. ______________ catalytic reaction is involved in the thermal cracking of gas oil ?

   A. Homogeneous
   B. Non-Homogeneous
   C. Heterogeneous
   D. Non-Heterogeneous

10. 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.