General Chemistry I — 2025A Past Questions

University of Ilorin CHM102: 83 questions.

Topics: Isolation, purification, and determination of organic compound structures., Introduction to transition metal chemistry., Electronic theory in organic chemistry., Nomenclature and functional group classes of organic compounds., Chemistry of alkanes, alkenes, alkynes, alcohols, ethers, amines, alkyl halides, nitriles, aldehydes, ketones, carboxylic acids, and derivatives., Introductory reaction mechanisms and kinetics., Fullerenes as the fourth allotrope of carbon (nanotubules, nanostructures, nanochemistry)., Chemistry of selected metals and non-metals., Nomenclature and functional group classes of organic compounds

1. Name the compound above
   1. 4-methylene-2-methylhexane
   2. 3-methylene-5-methylhexane
   3. 5-methylhex-3-ene
   4. None of the above
2. What year was the fullerene molecule discovered?
   1. 1980
   2. 1985
   3. 1990
   4. 1995
3. In the Beilstein test, the presence of a halogen is indicated by which flame color?
   1. Yellow flame
   2. White flame
   3. Blue-green flame
   4. Brick-red flame
4. In Lassaigne's test, which precipitate color specifically indicates the presence of chlorine?
   1. White
   2. Pale yellow
   3. Yellow
   4. Blue-green
5. The lower reactivity of ethyne to electrophilic addition compared to ethene is primarily linked to what factor?
   1. Steric hindrance around the triple bond
   2. Instability of the carbocation intermediate
   3. High stability of the vinylic anion
   4. The presence of strong hydrogen bonds
6. Which of the following transition elements possesses the lowest enthalpy of atomization?
   1. Tungsten (W)
   2. Iron (Fe)
   3. Zinc (Zn)
   4. Manganese (Mn)
7. What factor is primarily responsible for the high boiling and melting points observed in transition metals?
   1. Weak Van der Waals forces
   2. Strong interatomic metallic bonding
   3. Low ionization energies
   4. Formation of covalent networks
8. A mixture of arsenic and iodine can be separated efficiently using which of the following techniques?
   1. Simple distillation
   2. Fractional crystallization
   3. Sublimation
   4. Differential extraction
9. The single carbon-carbon bonds in saturated alkanes are formed by the overlapping of which hybrid orbitals?
   1. sp
   2. sp²
   3. sp³
   4. dsp²
10. Which of the following gaseous hydrocarbons is biologically active and used commercially to accelerate the ripening of fruits?
    1. Methane
    2. Ethene
    3. Propane
    4. Ethyne
11. The strongest carbon-carbon bond length is formed by the axial overlapping of two carbon atoms with which hybridization?
    1. sp³
    2. sp²
    3. sp
    4. sp³d
12. Which monomer is polymerized to produce polypropene (polypropylene) plastics?
    1. Ethene
    2. Propene
    3. Butene
    4. Vinyl chloride
13. The complete catalytic hydrogenation of ethene in the presence of a metal catalyst like Ni, Pd, or Pt yields which compound?
    1. Ethyne
    2. Methane
    3. Ethane
    4. Ethanol
14. A functional group in an organic molecule can be described by any of the following EXCEPT?
    1. A single atom (e.g., halogens)
    2. A group of atoms (e.g., -OH, -COOH)
    3. Multiple covalent bonds (e.g., C=C, C≡C)
    4. A methyl or methylene group
15. Dichloromethane can be efficiently separated from water using which of the following physical separation methods?
    1. Fractional distillation
    2. Differential extraction
    3. Crystallization
    4. Paper chromatography
16. What is the correct IUPAC name for 'ethyl dimethyl methanol'?
    1. 2-methylbutan-2-ol
    2. 2,2-dimethylpropanol
    3. 3-methylbutan-2-ol
    4. pentan-2-ol
17. Which of the following conditions must be true for two solvents used in differential extraction?
    1. They must be miscible and have identical polarities
    2. They must be immiscible and have different polarities
    3. They must have identical boiling points
    4. They must form an azeotropic mixture
18. Which analytical technique is purely a physical method used heavily to determine the structure of organic compounds by analyzing conjugated pi electron systems?
    1. Lassaigne's test
    2. Fractional distillation
    3. UV spectrometry
    4. Differential extraction
19. What is the primary reason for the unusually high enthalpy of atomization seen in transition elements?
    1. Presence of large atomic radii
    2. Presence of unpaired d-electrons enabling strong metallic bonds
    3. Low effective nuclear charge
    4. Complete absence of s-orbital electrons
20. What separation technique is fundamentally based on the differences in solubility of the organic compound and its impurities in a suitable solvent?
    1. Sublimation
    2. Simple Distillation
    3. Crystallization
    4. Chromatography
21. What factor accounts for the stability of the oxidation states of lower transition elements?
    1. High electronegativity values
    2. Low energy difference between successive oxidation states
    3. Inert pair effect
    4. Absence of d-orbitals
22. The vinylic C-H bond of propene (CH₃-CH=CH₂) is formed by the overlapping of the 1s orbital of hydrogen with which orbital of carbon?
    1. sp orbital
    2. sp³ orbital
    3. sp² orbital
    4. dsp orbital
23. Which combined electronic effects strongly act to stabilize a tertiary carbonium ion (carbocation)?
    1. Negative inductive and mesomeric effects
    2. Hyperconjugation and positive inductive effects
    3. Negative inductive and resonance effects
    4. Steric hindrance and negative mesomeric effects
24. Across the d-block series, atomic radii decrease initially, but then become relatively constant towards the end of the series. What causes this constancy?
    1. Rapid decrease in effective nuclear charge
    2. Variable oxidation states neutralizing the size
    3. Balance between effective nuclear charge and the screening effect of d-electrons
    4. Increase in the principal quantum number
25. In a laboratory sublimation apparatus, what is the purpose of placing an inverted glass funnel over the evaporating dish?
    1. To hasten the heating process
    2. To rapidly evaporate the sublimed vapour
    3. To provide a cool surface for the vapour to deposit and solidify
    4. To measure the vapour pressure
26. Which of the following metallic ions does NOT appear colored in aqueous solution?
    1. Fe²⁺
    2. Mn²⁺
    3. Cr³⁺
    4. Cu⁺
27. The Lassaigne's test (sodium fusion test) is commonly used to detect the presence of which elements in organic compounds?
    1. Carbon and Hydrogen
    2. Nitrogen, Sulphur, and Halogens
    3. Oxygen and Silicon
    4. Alkali metals and Alkaline earth metals
28. Which of the hybridized orbitals of carbon is considered the least electronegative?
    1. sp
    2. sp²
    3. sp³
    4. dsp²
29. Among the 3d transition series, which element generally exhibits the highest paramagnetic moment?
    1. Iron
    2. Cobalt
    3. Manganese
    4. Zinc
30. What is the primary reason transition elements and their compounds act as excellent heterogeneous and homogeneous catalysts?
    1. Their ability to sublime easily at low temperatures
    2. Their extremely low melting points
    3. Their variable oxidation states and ability to form coordination complexes
    4. Their high ionization energies
31. The carbon-carbon double bond in prop-1-ene (CH₂=CH-CH₃) is formed by the overlapping of which specific hybrid orbitals?
    1. sp³ and sp³
    2. sp³ and sp²
    3. sp² and sp²
    4. sp and sp²
32. In IUPAC nomenclature, what suffix is used to denote the presence of a carboxylic acid functional group?
    1. -al
    2. -one
    3. -oate
    4. -oic acid
33. Which reagent is commonly used as a chemical test to distinguish between a saturated alkane and an unsaturated alkene?
    1. Ammonium molybdate
    2. Bromine water
    3. Tollens' reagent (Silver mirror test)
    4. Sodium metal
34. Heterolytic fission of the C-Cl bond in 2-chloropropane yields what classification of carbocation?
    1. Primary (1°) carbocation
    2. Secondary (2°) carbocation
    3. Tertiary (3°) carbocation
    4. Allylic carbocation
35. What factor primarily causes the notable acidity of the terminal hydrogen atoms connected to an ethyne molecule?
    1. The highly polar nature of the C-C bond
    2. The low electronegativity of carbon
    3. The high s-character (50%) of the sp hybridized carbon increasing its electronegativity
    4. The hyperconjugation effect from adjacent atoms
36. Which of the following electronic effects tends to reduce the acidity of organic carboxylic acids?
    1. Negative inductive effect (-I)
    2. Positive inductive effect (+I)
    3. Resonance effect
    4. Negative mesomeric effect (-M)
37. A compound 'A' reacts with sodium metal to evolve hydrogen gas and form compound 'B'. When 'A' is heated with concentrated H₂SO₄ at 140°C, diethyl ether is formed. What is compound 'A'?
    1. CH₃OH
    2. C₂H₅OH
    3. C₃H₇OH
    4. C₂H₅COOH
38. Which purification method is most appropriate for separating two miscible liquids with a boiling point difference of strictly greater than 25°C?
    1. Fractional distillation
    2. Simple distillation
    3. Vacuum distillation
    4. Steam distillation
39. What is the correct IUPAC nomenclature for the highly branched molecule 'ethyl methyl propyl methane'?
    1. 2-ethylpentane
    2. 3-methylhexane
    3. 2-propylbutane
    4. 3-ethylhexane
40. In a simple distillation setup, what is the specific piece of apparatus used to cool down and condense the hot vapour back into a liquid phase?
    1. Fractionating column
    2. Theoretical plate
    3. Extractor
    4. Condenser
41. Which of the following organic functional classes are inherently formed by combining a carbonyl group (C=O) with a methoxy/alkoxy group (-OR)?
    1. Ketones
    2. Carboxylic acids
    3. Esters
    4. Amides
42. What reagent is specifically added to the sodium fusion extract (Lassaigne's extract) and heated with nitric acid to confirm the presence of phosphorus?
    1. Silver nitrate
    2. Ferric chloride
    3. Ammonium molybdate
    4. Lead acetate
43. Among the straight-chain alkanes listed below, which possesses the highest boiling point?
    1. Methane
    2. Ethane
    3. Butane
    4. Octane
44. What is the specific IUPAC nomenclature for the historically named 'tetramethylmethane'?
    1. 2-methylbutane
    2. 2,2-dimethylpropane
    3. 2,3-dimethylbutane
    4. Pentane
45. During the qualitative elemental analysis of organic compounds, carbon and hydrogen are typically detected by heating the compound with which specific oxidizing agent?
    1. Iron (II) oxide
    2. Copper (II) oxide
    3. Zinc oxide
    4. Silver nitrate
46. Which of the following organic gases is combined with oxygen to produce the extremely high temperatures used in oxy-acetylene welding torches?
    1. Methane
    2. Propane
    3. Ethene
    4. Ethyne
47. A mixture containing petroleum (gasoline) and water can be most easily and practically separated using which technique?
    1. Fractional distillation
    2. Simple distillation
    3. Differential extraction
    4. Crystallization
48. Which separation method is specifically required for mixtures of miscible liquids that have a very close boiling point difference (typically less than 25°C)?
    1. Steam distillation
    2. Simple distillation
    3. Vacuum distillation
    4. Fractional distillation
49. What is the molecular formula of the heterocyclic organic compound Tetrahydrofuran (THF)?
    1. C₄H₈O
    2. C₄H₄O
    3. C₅H₁₀O
    4. C₆H₆O
50. What fundamental structural factor favors the higher acidity of phenol compared to an aliphatic alcohol like ethanol?
    1. Positive inductive effect of the ring
    2. Conjugative effect
    3. Resonance stabilization of the phenoxide ion
    4. Sp³ hybridization of the adjacent carbon
51. Choose the correct decreasing order of acidic strength among the following substituted haloacetic acids:
    1. CH₃COOH > CH₂FCOOH > CH₂ClCOOH > CH₂BrCOOH
    2. CH₂FCOOH > CH₂ClCOOH > CH₂BrCOOH > CH₃COOH
    3. CH₂BrCOOH > CH₂ClCOOH > CH₂FCOOH > CH₃COOH
    4. CH₂ClCOOH > CH₂BrCOOH > CH₂FCOOH > CH₃COOH
52. Which of the following statements accurately describes the fundamental requirement for differential extraction?
    1. The solvents used must be highly miscible
    2. The separation relies on the identical densities of the liquids
    3. It involves the separation of components using two immiscible liquids with different polarities
    4. It requires the two liquid phases to have identical boiling points
53. Which physical property of the 3d transition metals decreases across the series until Manganese (Mn) and then gradually becomes relatively constant?
    1. First ionization energy
    2. Atomic radius
    3. Maximum oxidation state
    4. Electronegativity
54. Among the primary hybridizations of carbon, which one exhibits the highest electronegativity?
    1. sp
    2. sp²
    3. sp³
    4. sp³d
55. Which of the following designations is NOT a valid form of hybridization for a carbon atom in standard organic compounds?
    1. sp
    2. sp²
    3. sp³
    4. dsp²
56. Which of the following options correctly lists a set of organic compounds that ALL contain a carbonyl (C=O) functional group?
    1. Alcohols, amides, esters, alkanoic acids
    2. Alkanones, alkanamides, esters, alkanoic acids
    3. Alkanes, alkenes, alkynes, ethers
    4. Phenols, amines, nitriles, alkyl halides
57. Which of the following transition metal ions is diamagnetic (possesses no unpaired d-electrons)?
    1. Co²⁺
    2. Fe²⁺
    3. Cu²⁺
    4. Zn²⁺
58. Which of the following transition elements can achieve a highly stable +7 oxidation state due to its valence electron configuration?
    1. Chromium (Cr)
    2. Manganese (Mn)
    3. Iron (Fe)
    4. Cobalt (Co)
59. Terminal alkynes possess a weakly acidic vinylic hydrogen. Because of this specific property, they react selectively with which of the following?
    1. Pure water
    2. Dilute inorganic acids
    3. Aliphatic alcohols
    4. Active metals like sodium
60. Which of the following elements is strictly NOT classified as a member of the first (3d) transition series?
    1. Nickel (Ni)
    2. Silver (Ag)
    3. Chromium (Cr)
    4. Iron (Fe)
61. Why do the melting points of transition elements typically peak around the middle of the transition series (e.g., Chromium, Molybdenum)?
    1. They possess the largest atomic radii in the series
    2. They exhibit stronger metallic bonding due to the maximum number of unpaired d-electrons
    3. They possess the lowest ionization energies
    4. They have completely filled d-orbitals which stabilizes the lattice
62. The longest and weakest C-C single bond in an organic molecule is generated by the overlap of which two specific hybrid orbitals?
    1. sp³ and sp³
    2. sp² and sp²
    3. sp and sp
    4. sp² and sp³
63. What is the general structural formula for the functional group characteristic of alkanoyl (acyl) halides?
    1. -COOH
    2. -COOR
    3. -COX (where X is a halogen)
    4. -CONH₂
64. An organic compound consisting primarily of carbon and hydrogen, but incorporating at least one heteroatom (such as oxygen, nitrogen, or a halogen), is broadly classified as a:
    1. Saturated hydrocarbon
    2. Unsaturated hydrocarbon
    3. Hydrocarbon derivative
    4. Allotrope
65. What primary electronic effect exerted by alkyl chains increases the basicity of aliphatic amines relative to ammonia?
    1. Negative inductive effect (-I)
    2. Positive inductive effect (+I)
    3. Negative mesomeric effect (-M)
    4. Electromeric effect (+E)
66. The substitution of an alkyl hydrogen with an electron-withdrawing halogen significantly increases the acidity of alkanoic acids. This occurs primarily due to which electronic effect?
    1. Negative inductive effect (-I)
    2. Positive inductive effect (+I)
    3. Resonance stabilization (+R)
    4. Hyperconjugation
67. What specific class of carbonium ion (carbocation) is generated upon the heterolytic cleavage of the C-Cl bond in 2-chloro-2-methylpropane?
    1. Primary carbocation
    2. Secondary carbocation
    3. Tertiary carbocation
    4. Allylic carbocation
68. In the molecule prop-1-ene (CH₂=CH-CH₃), the specific carbon-carbon single sigma bond connecting the double-bonded carbon to the terminal allylic methyl group is formed by the overlapping of which orbitals?
    1. sp and sp²
    2. sp² and sp²
    3. sp² and sp³
    4. sp³ and sp³
69. Which specific oxidation state of Iron (Fe) demonstrates enhanced stability in aqueous solutions strictly due to its resulting symmetrical, half-filled 3d electron configuration?
    1. Fe⁺
    2. Fe²⁺
    3. Fe³⁺
    4. Fe⁴⁺
70. Applying standard IUPAC nomenclature rules for polyfunctional molecules, which of the following sequences correctly arranges the groups in order of strictly increasing priority?
    1. Carboxylic Acid < Amide < Aldehyde < Ketone
    2. Ketone < Aldehyde < Amide < Carboxylic Acid
    3. Aldehyde < Ketone < Carboxylic Acid < Amide
    4. Amide < Carboxylic Acid < Ketone < Aldehyde
71. How does the paramagnetic moment generally behave as you traverse from left to right across the 3d transition series elements?
    1. It remains completely constant throughout the series
    2. It strictly decreases from Scandium to Zinc
    3. It increases up to the middle of the series (Cr/Mn) and then steadily decreases
    4. It decreases up to Chromium and then increases rapidly toward Zinc
72. Which combination of electronic displacement effects heavily favors the stabilization of an alkyl carbonium ion (carbocation)?
    1. Negative inductive effect and negative mesomeric effect
    2. Hyperconjugation and positive inductive effect
    3. Resonance effect and negative inductive effect
    4. Electromeric effect and negative inductive effect
73. Mechanistically, the chemical reaction between an unsaturated alkene and bromine water (to yield a dibromoalkane) is classified as what specific type of reaction?
    1. Nucleophilic substitution
    2. Electrophilic addition
    3. Free radical substitution
    4. Elimination reaction
74. Structurally, an alkanonitrile (R-C≡N) is conceptually considered a functional derivative of which parent class of organic compounds?
    1. Alkene
    2. Alkyne
    3. Alkane
    4. Alcohol
75. Which of the following terms is NOT a formally recognized classification of structural formulas used to visually represent organic chemistry molecules?
    1. Expanded structural formula
    2. Condensed structural formula
    3. Skeletal (line-angle) formula
    4. Built structural formula
76. Among the primary hybrid orbitals assumed by carbon, which one acts as the least electronegative due to possessing the lowest proportional s-character?
    1. sp
    2. sp²
    3. sp³
    4. 2p
77. Which of the following transition metal ions lacks the ability to undergo d-d electronic transitions and, as a direct consequence, appears completely colorless in aqueous solution?
    1. Sc²⁺
    2. Ti³⁺
    3. Fe²⁺
    4. Cu⁺
78. Which of the following transition elements possesses the absolute highest melting point of all metals, making it the primary choice for incandescent lightbulb filaments?
    1. Cadmium (Cd)
    2. Tungsten (W)
    3. Mercury (Hg)
    4. Zinc (Zn)
79. Which specific pair of elements exhibits nearly identical atomic radii, rendering them exceptionally difficult to separate, primarily due to the phenomenon of lanthanide contraction?
    1. Zirconium (Zr) and Hafnium (Hf)
    2. Zirconium (Zr) and Tantalum (Ta)
    3. Zirconium (Zr) and Niobium (Nb)
    4. Zirconium (Zr) and Actinium (Ac)
80. A liquid mixture containing the absolute maximum measurable amount of dissolved solid solute it can possibly hold at a strict, given equilibrium temperature is termed a:
    1. Unsaturated solution
    2. Saturated solution
    3. Supersaturated solution
    4. Dilute solution
81. The successful purification of an impure solid organic compound via crystallization relies heavily on the solute exhibiting what precise solubility behavior?
    1. It must dissolve readily in cold solvent but remain sparingly soluble in boiling solvent
    2. It must dissolve completely in hot solvent but remain sparingly soluble when the solvent is cold
    3. It must dissolve equally and completely in both freezing and boiling solvent
    4. It must precipitate completely upon heating the solvent
82. During the chemical execution of Lassaigne's test, the appearance of a distinct blood-red coloration upon the introduction of ferric chloride directly proves the simultaneous presence of which two elements in the tested organic compound?
    1. Nitrogen and Oxygen
    2. Nitrogen and Sulphur
    3. Sulphur and Halogens
    4. Nitrogen and Phosphorus
83. Which specific distillation technique is strictly required to successfully purify liquids that inherently possess very high boiling points and exhibit the tendency to thermally decompose at or even slightly below their standard atmospheric boiling temperatures?
    1. Steam distillation
    2. Fractional distillation
    3. Vacuum distillation (distillation under reduced pressure)
    4. Simple distillation

Register free to unlock all 83 questions with answers and explanations