MCQ Collection
MDCAT Chemistry MCQs
Practice MDCAT Chemistry questions with answers and explanations.
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Correct Answer: D. -120 kJ mol⁻¹
Explanation:
Hess’s law states that enthalpy changes add for sequential steps.
The overall value is the algebraic sum of the two changes.
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Correct Answer: A. -150 kJ mol⁻¹
Explanation:
Hess’s law states that enthalpy changes add for sequential steps.
The overall value is the algebraic sum of the two changes.
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Correct Answer: B. -50 kJ mol⁻¹
Explanation:
Hess’s law states that enthalpy changes add for sequential steps.
The overall value is the algebraic sum of the two changes.
Choose an option to check your answer.
Correct Answer: C. -150 kJ mol⁻¹
Explanation:
Hess’s law states that enthalpy changes add for sequential steps.
The overall value is the algebraic sum of the two changes.
Choose an option to check your answer.
Correct Answer: D. 300 J
Explanation:
The first law conserves energy: ΔU = q − w for work done by the system.
Substitution gives the stated internal-energy change.
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Correct Answer: B. Activation energy decreases
Explanation:
Reaction rate depends on effective collision frequency and activation energy.
The stated change follows from collision theory.
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Correct Answer: C. A larger fraction of molecules exceeds activation energy
Explanation:
Reaction rate depends on effective collision frequency and activation energy.
The stated change follows from collision theory.
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Correct Answer: D. Available surface area increases
Explanation:
Reaction rate depends on effective collision frequency and activation energy.
The stated change follows from collision theory.
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Correct Answer: A. Collision frequency generally increases
Explanation:
Reaction rate depends on effective collision frequency and activation energy.
The stated change follows from collision theory.
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Correct Answer: B. The number of effective catalytic sites decreases
Explanation:
Reaction rate depends on effective collision frequency and activation energy.
The stated change follows from collision theory.
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Correct Answer: A. 0.02 mol L⁻¹ s⁻¹
Explanation:
Average disappearance rate = decrease in concentration divided by time.
The positive magnitude is used for a reactant-disappearance rate.
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Correct Answer: B. 0.03 mol L⁻¹ s⁻¹
Explanation:
Average disappearance rate = decrease in concentration divided by time.
The positive magnitude is used for a reactant-disappearance rate.
