Chemical Kinetics Mock Test – Class 12 Chemistry

1. A catalyst lowers the activation energy from to . Assuming the same pre-exponential factor, the ratio at is closest to:

2. An energy profile has and . The reverse activation energy is:

3. A mechanism contains a fast step followed by the slow elementary step . Why is not usually accepted as the final overall rate law?

4. In the rate law , the rate constant is:

5. The table lists values of for the same reaction at three temperatures.

Assuming the same , the order of rate constants is:

6. A proposed mechanism is:


Writing as the final experimentally usable rate law is incomplete because:

7. Assertion: The slope of an Arrhenius plot of against is negative, although activation energy is positive.
Reason: The slope is equal to .

8. Reaction order is assessed through the statements below.
Statement I: An overall order may be zero.
Statement II: An overall order may be fractional.
Statement III: Every overall reaction must have a positive whole-number order.
The valid statements are:

9. Assertion: The average rate of disappearance of a reactant is conventionally reported as a positive quantity.
Reason: During forward reaction progress, the concentration change of a consumed reactant is negative.

10. A linear zero-order concentration-time graph has vertical intercept and slope . The extrapolated time-axis intercept is:

11. Match each quantity in Column I with its usual unit or symbol in Column II.

12. According to collision theory, a chemical reaction can occur when reactant particles:

13. Reaction rate is quantitatively described as:

14. Which description best represents a graph of against absolute temperature for an ordinary reaction with positive activation energy?

15. A zero-order reaction and a first-order reaction begin with the same reactant concentration and the same initial rate. At a later time, both reactions are still proceeding and the zero-order reaction remains within its valid kinetic regime. Their rates are then best compared by stating that:

16. For zero-order disappearance, and . The concentration after is:

17. A concentration-time line for zero-order disappearance has slope and vertical intercept . Its half-life and idealised completion time are:

18. When the temperature of a reacting system is raised while concentrations and other conditions are kept unchanged, the reaction rate generally:

19. During an interval, a reactant concentration decreases from to . Its average rate of disappearance is:

20. The following average disappearance rates were obtained for successive intervals of the same reaction.

The data support the conclusion that:

21. A process has a negative Gibbs energy change under certain conditions but proceeds extremely slowly. This observation shows that:

22. Which feature may appear on a catalysed energy profile even when the uncatalysed profile has only one peak?

23. When is held constant for the rate law , the missing exponent in the rate-ratio relation is ______.

24. The units of rate constants are assessed through the statements below.
Statement I: The time dimension of is always reciprocal time for a rate law written in the usual concentration form.
Statement II: The concentration dimension of depends on the overall reaction order.
Statement III: The unit of reaction rate changes with reaction order.
The valid statements are:

25. Concentration-time data for a reaction are shown below.

If the reaction is zero order, the graph parameters are:

26. A student uses

for the reaction , where is the total pressure. The procedure is incorrect because:

27. Two experiments use identical initial concentrations and the same catalyst condition, but Experiment Q is performed at a higher temperature than Experiment P. If the reaction mechanism remains unchanged, the most likely result is:

28. Two energy-distribution curves P and Q correspond to the same gas sample at different temperatures. Curve Q has a lower maximum, is broader, and is shifted toward higher energy. Which comparison is correct?

29. The limiting relation that connects average and instantaneous rate is:

30. The rate is expressed as . Its unit indicates:

31. The instantaneous rate of a reaction at time is obtained conceptually by:

32. For the true rate law , one experiment uses approximately times . Which interpretation is most suitable?

33. Taking the natural logarithm of the Arrhenius equation

gives:

34. Match each collision-theory quantity in Column I with its description in Column II.

35. Four collisions differ in energy and orientation.

Which collision is effective according to collision theory?

36. An activation energy of is reported for a reaction whose rate constant at an unknown temperature is four times its value at . The unknown temperature is closest to:

37. At , a reaction has and . Using , the pre-exponential factor is closest to:

38. A surface reaction is zero order in reactant while the catalyst surface is saturated. When becomes very small, the rate begins to decrease with . This observation shows that:

39. Which statement best describes reaction order?

40. A secant and a tangent are drawn on the same curved reactant concentration-time graph. Their kinetic meanings are:

41. The measurements are made at identical reactant concentrations and otherwise identical conditions.
Rate data for a reaction are shown below.

Assuming a constant temperature coefficient over this range, its value is:

42. The correct two-temperature Arrhenius relation is:

43. For a first-order gas reaction , the pressure of remaining at time is represented by the blank:

when is the final total pressure.

44. The missing relation in the definition of the temperature coefficient is ______.

45. A rate law determined for a reaction at in the absence of a catalyst should be applied directly to another experiment only when:

46. On a straight-line Arrhenius plot of against , the point corresponding to the higher temperature lies:

47. A photochemical reaction is zero order in reactant while the absorbed light intensity remains constant. If the absorbed photon flux is doubled without changing other conditions, the rate is expected to:

48. Two reactions have Arrhenius parameters:

Which conclusion is most appropriate at a specified temperature?

49. The reported reaction rate is . The same rate expressed in is:

50. The half-life of a first-order reaction is independent of the initial reactant concentration because: