MCQ Collection
Pakistan MCQs
Practice Pakistan questions with answers and explanations.
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Correct Answer: A. Restricted rotation around the C=C bond
Explanation:
The pi bond prevents free rotation.
Each double-bond carbon must have two different substituents for geometric isomerism.
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Correct Answer: B. A saturated hydrocarbon containing only single C-C bonds
Explanation:
Alkanes are saturated because they contain the maximum number of hydrogens.
Their general acyclic formula is CnH2n+2.
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Correct Answer: B. Atoms or groups add across a multiple bond
Explanation:
Addition reactions reduce unsaturation.
Alkenes commonly undergo electrophilic addition.
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Correct Answer: C. A hydrocarbon containing at least one C=C double bond
Explanation:
Alkenes are unsaturated hydrocarbons.
Their double bond contains one sigma and one pi bond.
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Correct Answer: C. One atom or group is replaced by another
Explanation:
Substitution preserves much of the carbon skeleton.
Halogenation of alkanes is an example.
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Correct Answer: D. A hydrocarbon containing at least one C≡C triple bond
Explanation:
Alkynes are unsaturated hydrocarbons.
The triple bond contains one sigma and two pi bonds.
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Correct Answer: D. Removal of atoms or groups to form a multiple bond
Explanation:
Elimination often removes H and another group from adjacent atoms.
It commonly forms an alkene.
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Correct Answer: D. Electronic transitions within split d orbitals absorb visible light
Explanation:
Ligands split d-orbital energies.
Absorption of selected visible wavelengths gives the observed complementary color.
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Correct Answer: A. Their ns and (n-1)d electrons have similar energies
Explanation:
Both s and d electrons may participate in bonding or ion formation.
This permits several stable oxidation states.
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Correct Answer: B. An ion or molecule donating an electron pair to a metal center
Explanation:
Ligands act as Lewis bases.
They form coordinate covalent bonds with metal ions.
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Correct Answer: A. SO3
Explanation:
SO3 is a nonmetal oxide and forms sulfuric acid with water.
Metal oxides listed are predominantly basic.
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Correct Answer: B. Na2O
Explanation:
Sodium oxide reacts with water to form sodium hydroxide.
It is a strongly basic metal oxide.
