MCQ Collection
MDCAT 2026 MCQs
Practice MDCAT 2026 questions with answers and explanations.
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A.
At the anode
B.
In the wire only
C.
At the cathode
D.
In the solvent only
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Correct Answer: C. At the cathode
Explanation:
The mnemonic 'Red Cat' identifies reduction at the cathode.
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A.
Total mass of products
B.
Equilibrium constant
C.
Heat capacity
D.
Change in concentration of reactant or product per unit time
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Correct Answer: D. Change in concentration of reactant or product per unit time
Explanation:
Reaction rate measures how fast composition changes.
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A.
Carry electrons between electrodes
B.
Increase electrode mass only
C.
Stop all ion movement
D.
Maintain electrical neutrality by ion migration
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Correct Answer: D. Maintain electrical neutrality by ion migration
Explanation:
The salt bridge completes the internal ionic circuit.
Choose an option to check your answer.
A.
Dependence of reaction rate on reactant concentrations
B.
Stoichiometric coefficients only
C.
Equilibrium composition only
D.
Heat released by reaction
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Correct Answer: A. Dependence of reaction rate on reactant concentrations
Explanation:
A rate law is determined experimentally.
Choose an option to check your answer.
A.
Stoichiometric coefficient in every case
B.
Exponent of a concentration term in a rate law
C.
Number of products
D.
Activation energy
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Correct Answer: B. Exponent of a concentration term in a rate law
Explanation:
Reaction order may be zero, fractional, or integer.
Choose an option to check your answer.
A.
Total enthalpy of products
B.
Energy released by a catalyst
C.
Minimum energy barrier for a reaction pathway
D.
Bond energy of every reactant
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Correct Answer: C. Minimum energy barrier for a reaction pathway
Explanation:
Reacting particles need sufficient energy and orientation to form an activated complex.
Choose an option to check your answer.
A.
By increasing equilibrium constant
B.
By increasing product enthalpy
C.
By being permanently consumed
D.
By providing a pathway with lower activation energy
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Correct Answer: D. By providing a pathway with lower activation energy
Explanation:
A catalyst speeds both forward and reverse reactions.
Choose an option to check your answer.
A.
Higher temperature increases rate
B.
Higher temperature always decreases rate
C.
Temperature has no effect
D.
Only equilibrium changes, never rate
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Correct Answer: A. Higher temperature increases rate
Explanation:
Higher temperature increases collision frequency and energetic collisions.
Choose an option to check your answer.
A.
It always decreases rate
B.
It increases collision frequency and usually increases rate
C.
It changes only molar mass
D.
It eliminates activation energy
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Correct Answer: B. It increases collision frequency and usually increases rate
Explanation:
More particles per volume collide more often.
Choose an option to check your answer.
A.
It decreases rate
B.
It has no effect
C.
It usually increases rate
D.
It changes equilibrium constant only
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Correct Answer: C. It usually increases rate
Explanation:
More exposed particles are available for collision.
Choose an option to check your answer.
A.
Gain of electrons
B.
Gain of protons only
C.
Formation of a precipitate only
D.
Loss of electrons or increase in oxidation number
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Correct Answer: D. Loss of electrons or increase in oxidation number
Explanation:
Oxidation and reduction occur together.
Choose an option to check your answer.
A.
Gain of electrons or decrease in oxidation number
B.
Loss of electrons
C.
Loss of neutrons
D.
Increase in oxidation number
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Correct Answer: A. Gain of electrons or decrease in oxidation number
Explanation:
A reduced species accepts electrons.
