MCQ Collection
MDCAT 2026 MCQs
Practice MDCAT 2026 questions with answers and explanations.
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Correct Answer: B. A proton acceptor
Explanation:
A Brønsted-Lowry base accepts H+.
It forms its conjugate acid.
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Correct Answer: C. An electron-pair acceptor
Explanation:
Lewis theory focuses on electron-pair transfer.
Many metal ions and electron-deficient molecules act as Lewis acids.
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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: C. An acid that ionizes only partially in water
Explanation:
Weak-acid solutions contain both ionized and unionized forms.
They establish an equilibrium in water.
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Correct Answer: D. Negative logarithm of hydrogen-ion activity or approximate concentration
Explanation:
For dilute solutions, pH≈-log[H+].
Lower pH generally means greater acidity.
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Correct Answer: A. Liver
Explanation:
The liver produces bile continuously.
The gallbladder stores and concentrates it.
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Correct Answer: A. Negative logarithm of hydroxide-ion concentration
Explanation:
For dilute aqueous solutions, pOH=-log[OH-].
At 25°C, pH+pOH≈14.
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Correct Answer: B. -40 kJ
Explanation:
Use ΔG=ΔH-TΔS.
ΔG=-100-300(-0.20)=-40 kJ.
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Correct Answer: C. A solution that resists large pH changes
Explanation:
Buffers contain a weak acid-base pair.
They consume added H+ or OH-.
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Correct Answer: C. -30 kJ
Explanation:
Use ΔG=50-400(0.20).
ΔG=50-80=-30 kJ.
