Reaction Kinetics MCQs for MDCAT Practice

Chemistry section, Reaction Kinetics chapter. Sample questions from past PMC papers.

1. Question 1
   The branch of Chemistry that deals with the reactions rates and reaction mechanism is called:
   • A.Chemical Kinetics
   • B.Thermodynamics
   • C.Photochemistry
   • D.Analytical Chemistry
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2. Question 2
   The specific rate constant of a chemical reaction is the rate of the reaction when the concentration of the reactant is
   • A.Less than unity
   • B.Equal to unity
   • C.Greater than unity
   • D.Equal to the concentration of 2nd order reaction
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3. Question 3
   A substance that alters the rate of chemical reaction without being consumed in the reaction is called:
   • A.Catalyst
   • B.Reactant
   • C.Product
   • D.Activated complex
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4. Question 4
   Which of the following increases the rate of reaction?
   • A.Decrease temp
   • B.Decrease conc.
   • C.Increase surface area
   • D.Add inhibitor
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5. Question 5
   The sum of all the exponents (power) of the reactants in the rate expression is called:
   • A.Molecularity
   • B.Atomicity of the molecules
   • C.Order of reaction
   • D.None of the above
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6. Question 6
   If the graphic representation of the energy levels of the reactants and products in a chemical reaction looks like this: Which of the following statements are true? I. The activation energy for the forward reaction is represented by the “a” portion. II. The activation energy for the forward reaction is represented by the “b” portion of the graph. III. The “a” portion is the energy given off in the forward reaction.
   
   • A.II only
   • B.I and III only
   • C.II and III only
   • D.I only
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7. Question 7
   What is detailed sequence of steps that leads to the net overall reaction called?
   • A.Reaction coordinate
   • B.Reaction mechanism
   • C.Reaction potential
   • D.Reaction rate law
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8. Question 8
   In the termination step where two methyl radicals combine to form ethane (CH3. + .CH3 -> C2H6), the reaction typically has an activation energy of approximately zero. What is the logical reason for this?
   • A.The entropy of the universe decreases significantly.
   • B.There are no bonds to break and two open-shell electrons are pairing.
   • C.The reaction is endothermic.
   • D.Methyl radicals are stable species that drift together slowly.
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