MCQ Collection
Pakistan MCQs
Practice Pakistan questions with answers and explanations.
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Correct Answer: B. Graphite
Explanation:
Graphite has delocalized electrons within its layers.
These electrons allow electrical conduction.
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Correct Answer: C. 4
Explanation:
POH=-log(1×10^-4).
The result is 4.
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Correct Answer: C. Each carbon forms a rigid three-dimensional covalent network
Explanation:
Every carbon is tetrahedrally bonded to four others.
The extended network resists deformation.
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Correct Answer: D. 9
Explanation:
At 25°C, pH+pOH=14.
POH=14-5 = 9.
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Correct Answer: D. An oxide that reacts with both acids and bases
Explanation:
Amphoteric oxides can behave as acidic or basic substances.
Aluminum oxide and zinc oxide are examples.
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Correct Answer: A. 0.40 M
Explanation:
Moles NaOH=0.0200×0.50=0.0100 mol.
The HCl concentration is 0.0100/0.0250=0.40 M.
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Correct Answer: B. 0.10 M/s
Explanation:
For first order, rate=k[A].
Rate=0.20×0.50=0.10 M/s.
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Correct Answer: C. 4
Explanation:
The rate depends on the square of concentration.
Doubling gives 2²=4 times the rate.
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Correct Answer: D. Gain of electrons or decrease in oxidation number
Explanation:
A reduced species accepts electrons.
Reduction accompanies oxidation.
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Correct Answer: A. A species that causes oxidation and is itself reduced
Explanation:
The oxidizing agent accepts electrons.
Its oxidation number decreases.
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Correct Answer: B. A species that causes reduction and is itself oxidized
Explanation:
The reducing agent donates electrons.
Its oxidation number increases.
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Correct Answer: C. An electrochemical cell producing electrical energy from a spontaneous reaction
Explanation:
A galvanic or voltaic cell converts chemical energy into electrical energy.
Electrons flow through an external circuit.
