Reactions with high activation energy are_____________________?

Related Mcqs:

1. 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

2. 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

3. The reactions with low activation energy are _____________________?

   A. Always spontaneous
   B. Slow
   C. Fast
   D. Non-spontaneous

4. 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

5. 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

6. 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

7. The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is________________________?

   A. Backmix reactor
   B. Plug flow reactor
   C. Series of CSTR
   D. PFR in series

8. 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.

9. When the reaction occurs in the diffusion controlled region, the apparent activation energy as measured is only _______________ the true value?

   A. Twice
   B. Half
   C. Equal
   D. None of these

10. 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