MCQ Collection
MDCAT Chemistry MCQs
Practice MDCAT Chemistry questions with answers and explanations.
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Correct Answer: D. An electron-pair donor
Explanation:
Lewis bases donate a lone pair to form a coordinate bond.
Ammonia is a common example.
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Correct Answer: A. Two species differing by one proton
Explanation:
An acid forms its conjugate base after donating H+.
A base forms its conjugate acid after accepting H+.
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Correct Answer: B. An acid that ionizes essentially completely in water
Explanation:
Strength refers to extent of ionization, not concentration.
Strong acids produce hydronium ions nearly completely.
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Correct Answer: D. -125 kJ/mol
Explanation:
Heat release gives a negative enthalpy sign.
-250 kJ divided by 2 mol equals -125 kJ/mol.
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Correct Answer: A. 4180 J
Explanation:
Use q=mcΔT.
Q=100×4.18×10 = 4180 J.
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Correct Answer: B. 1.0 J/g·°C
Explanation:
Use c=q/(mΔT).
C=1000/(50×20)=1.0 J/g·°C.
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Correct Answer: D. A process thermodynamically favored under specified conditions
Explanation:
Spontaneity describes direction, not speed.
A spontaneous reaction may still be very slow.
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Correct Answer: A. A thermodynamic function used to predict spontaneity at constant temperature and pressure
Explanation:
Gibbs energy change is ΔG=ΔH-TΔS.
Negative ΔG indicates a thermodynamically favorable direction.
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Correct Answer: B. ΔG = 0
Explanation:
At equilibrium there is no net driving force for change.
The reaction mixture has minimum Gibbs energy under the conditions.
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Correct Answer: C. Dynamic state where forward and reverse reaction rates are equal
Explanation:
At equilibrium, concentrations remain constant over time.
Molecules continue reacting in both directions.
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Correct Answer: D. A ratio of product and reactant activities at equilibrium
Explanation:
The equilibrium expression follows stoichiometric powers.
Its value depends on temperature.
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Correct Answer: A. Products are strongly favored at equilibrium
Explanation:
A large K means the equilibrium mixture contains mostly products.
It does not directly indicate reaction speed.
