General Chemistry I — 2025C Past Questions

University of Ilorin CHM101: 52 questions.

Topics: Hybridisation and shapes of simple molecules, Chemical equations and stoichiometry, Elementary thermochemistry, Redox reactions and introduction to electrochemistry, Acids, bases and salts, Modern electronic theory of atoms, Radioactivity, Chemical bonding and intermolecular forces, Electronic configuration, Properties of gases, Atoms, elements, molecules, Kinetic theory of matter, Periodicity and building up of the periodic table

  1. Calculate the standard cell potential produced by a voltaic cell consisting of a sodium electrode in contact with a solution of Na+ and a copper electrode in contact with a solution of Cu2+ ions. Reduction (Cu2+ + 2e− → Cu) = 0.34V, Oxidation (Na → Na+ + e−) = -2.71V
    1. -2.36V
    2. 2.36V
    3. 3.05V
    4. -3.05V
  2. Reaction of dimethyl sulphide is 83% efficient. What is the mass of CH3SO2 that will be produced if 65g of dimethyl sulphide is used?
    1. 54.8g
    2. 45.2g
    3. 60.0g
    4. 70.0g
  3. Which of the following is the unhybridized orbital in sp2 carbon hybridization?
    1. 2Px
    2. 2Py
    3. 2Pz
    4. All of the above
  4. Find the coefficient of oxygen in the balanced chemical reaction of NH3 + O2 → NO2 + H2O
    1. 1
    2. 4
    3. 3
    4. 7
  5. In which of the following will the reaction occur rapidly?
    1. Between ions in aqueous solution because little energy is needed to break the bonds since the ions are already dissociated
    2. Between all gases because they have greater average kinetic energy
    3. Between solids because they are closely packed
    4. Between liquids because they have moderate kinetic energy
  6. Each of the reactants has a mass of 5g. Which of the following specie is the limiting reactant in the equation: 2KMnO4 + 5Hg2Cl2 + 16HCl → 2MnCl2 + 10HgCl2 + 8H2O + 2KCl?
    1. Hg2Cl2
    2. KMnO4
    3. H2O
    4. HCl
  7. Which of the following about a catalyst is correct? I. Creates new path for reaction II. Lowers activation energy of the reaction III. Reduces concentration of reactant IV. Remains unchanged after reaction
    1. I and II
    2. II and III
    3. III and IV
    4. II and IV
  8. Which of the following shows the sp2 hybridization of carbon?
    1. 1s² 2s² 2p²
    2. 1s² 2s¹ 2px¹ 2pz¹
    3. 1s² 2s¹ 2px¹ 2py¹ 2pz¹
    4. 1s² 2s² 2py¹ 2pz¹
  9. If an endothermic reaction is placed in air, the temperature of the surrounding will ___ with time.
    1. Decrease
    2. Increase
    3. Remain constant
    4. Zero
  10. Temperature change in a chemical reaction is as a result of exchange of heat:
    1. Between system and surrounding
    2. Between system and universe
    3. Between universe and surrounding
    4. Within the system
  11. Arrange in the order of proximity to the nucleus:
    1. sp < sp² < sp³
    2. sp > sp² > sp³
    3. sp³ < sp² < sp
    4. sp² < sp < sp³
  12. If E° of a cell is -1.00V, the reaction is:
    1. Spontaneous
    2. Non-spontaneous
    3. Has ∆G to be +ve
    4. Has ∆G to be -ve
  13. Convert 123°C to Kelvin.
    1. 396K
    2. 400K
    3. 350K
    4. 273K
  14. What is the correct order of the number of lone pairs for the following: O3, H2O, and CO2?
    1. 2, 4, 0
    2. 2, 1, 4
    3. 4, 0, 2
    4. 2, 4, 1
  15. For a reaction to be spontaneous, ∆E is:
    1. <0
    2. >0
    3. 0
    4. ≥0
  16. Px, Py, and Pz are referred to as degenerate orbitals because:
    1. They have the same energy level
    2. They have the same orientation
    3. They have different shapes
    4. They have different energies
  17. In an alpha radiation, the nuclei experience:
    1. Decrease in mass number by 4 and increase in atomic number by 2
    2. Decrease in mass number by 4 and decrease in atomic number by 2
    3. Increase in atomic number by 2 and increase in mass number by 4
    4. No change in mass or atomic number
  18. Unit for rate constant of zero order is given as:
    1. s⁻¹
    2. L·s⁻¹
    3. mol·L⁻¹·s⁻¹
    4. mol·s⁻¹
  19. In a zero-order reaction, rate constant is independent of concentration of the reactants.
    1. True
    2. False
    3. Can't be determined
    4. Depends on temperature
  20. What will be the graphical representation of a zero-order reaction?
    1. Linear graph of ln[A] vs t, positive slope
    2. Linear graph of [A] vs t, positive slope
    3. Linear graph of [A] vs t, negative slope
    4. Curved graph of ln[A] vs t, positive slope
  21. If two orbitals have the same (n + l) values, the one with the lower energy has lower:
    1. Magnetic quantum number
    2. Spin quantum number
    3. Azimuthal quantum number
    4. Principal quantum number
  22. Balance the chemical equation: Cr2(SO4)3 + RbOH → Cr(OH)3 + Rb2SO4. What is the sum of the coefficients?
    1. 13
    2. 12
    3. 11
    4. 14
  23. What is the molecular geometry of silane (SiH4)?
    1. Octahedral
    2. Trigonal bipyramidal
    3. Tetrahedral
    4. Square planar
  24. What is the electronic configuration of Carbon?
    1. 1s² 2s² 2px²
    2. 1s² 2s¹ 2px¹ 2py¹ 2pz¹
    3. 1s² 2s² 2px¹ 2py¹
    4. 1s² 2s² 2p²
  25. Calculate the mass of copper deposited at the cathode in the electrolysis of CuSO4 by 1F (Cu = 63.5).
    1. 31.75g
    2. 63.5g
    3. 15.875g
    4. 127g
  26. Calculate the number of Faradays used in the deposition of 21.58g of Ag at the cathode (Ag = 107.9).
    1. 0.20F
    2. 0.40F
    3. 0.10F
    4. 0.50F
  27. Calculate the volume if the pressure is 1×10⁵ kPa, the number of moles is 1 mole (of CO2), and the temperature is 298K (R = 8.314).
    1. 0.0248 m³
    2. 0.0486 m³
    3. 0.0124 m³
    4. 0.0312 m³
  28. Calculate the value of 6.00% of NiSO4 in a solution that contains 40g of NiSO4.
    1. 2.40g
    2. 4.00g
    3. 6.00g
    4. 8.00g
  29. Which of the following has the same number of electrons as Ne?
    1. K⁺
    2. O²⁻
    3. Na
    4. Mg⁺
  30. Which of the following is a measure of the strength of an acid?
    1. Concentration
    2. Degree of ionization
    3. pH
    4. Volume
  31. Which of the following is not true about alpha particles?
    1. They have high ionization power
    2. They have very low penetration power
    3. They have moderate penetration power
    4. They are negatively charged and are deflected towards the south
  32. Which of the following refers to the breakdown of a heavy isotope by a nucleus into two or more smaller isotopes with the release of energy?
    1. Nuclear transmutation
    2. Electron capture
    3. Nuclear fission
    4. Nuclear fusion
  33. What is the hybridization of alkanes?
    1. sp
    2. sp²
    3. sp³
    4. sp³d
  34. Which heat change is the most positive?
    1. Combustion
    2. Vaporization
    3. Fusion
    4. Sublimation
  35. Which endothermic change will be the greatest for 5g of H2O?
    1. Condensation
    2. Melting
    3. Vaporization
    4. Freezing
  36. The physical property that differentiates atoms which are isotopes is:
    1. Electronic configuration
    2. Mass number
    3. Atomic number
    4. Chemical properties
  37. A voltaic cell houses the reaction between Br2(aq) and Zn: Br2(aq) + Zn(s) → Zn²⁺(aq) + 2Br⁻(aq). E°cell = 1.83V. Calculate E°Br, given E°Zn = -0.76V.
    1. 2.59V
    2. 1.07V
    3. 0.76V
    4. -1.07V
  38. The oxidation state of the metal in MnO4⁻ and MnO2 is:
    1. +7 and +2
    2. -7 and -4
    3. -3 and -5
    4. +7 and +4
  39. How many sigma bonds are present in sp³ hybridization?
    1. 2
    2. 3
    3. 4
    4. 5
  40. In the compound CuSO4²⁻, what contributes to the acidity?
    1. Cu
    2. SO4²⁻
    3. Both
    4. Neither
  41. How many sigma bonds are in sp³d² hybridization with square planar geometry?
    1. 5
    2. 4
    3. 6
    4. 3
  42. What is the steric number for H2O and the H-O-H bond angle?
    1. 3, 120°
    2. 4, 109.5°
    3. 2, 180°
    4. 5, 60.5°
  43. Na2CO3(s) → Na2CO3(aq) ∆H = +x kJ/mol. This thermochemical equation under standard conditions represents:
    1. Standard enthalpy of dissolution
    2. Standard enthalpy of hydration
    3. Standard enthalpy of condensation
    4. Standard enthalpy of formation
  44. Plasma to gas is:
    1. Polarization
    2. Vaporization
    3. Deposition
    4. Recombination
  45. What is the bond angle of a seesaw (AX4E) molecule?
    1. 90°
    2. 120°
    3. 109.5°
    4. 180°
  46. The binary acid that has the highest acidity?
    1. H2Te
    2. H2O
    3. H2Se
    4. H2S
  47. Sum of the quantum numbers on the last electron of lithium.
    1. 2
    2. 5/2
    3. 3/2
    4. 1
  48. Which of the following is carbon sp³ hybridized?
    1. C-C single bond
    2. C=C double bond
    3. C≡C triple bond
    4. All of the above
  49. HOBr + OH⁻ → H2O + OBr⁻. What are the Brønsted-Lowry base species?
    1. H2O & OH⁻
    2. OH⁻ & OBr⁻
    3. HOBr & H2O
    4. OBr⁻ & HOBr
  50. A first-order reaction has a half-life of 138s. Calculate the time taken for the compound to decrease from 1.28 mmol to 0.040 mmol.
    1. 690s
    2. 609s
    3. 960s
    4. 906s
  51. The reaction of H2S + SO2 → S + H2O. From this, the order of reaction is:
    1. 1st order
    2. 2nd order
    3. 3rd order
    4. Cannot be determined
  52. Which of the following is a zero-order reaction?
    1. Radioactive decay
    2. Decomposition of hydrogen iodide (2HI → H₂ + I₂)
    3. The decomposition of ammonia (NH₃) on a hot platinum (Pt) surface
    4. Hydrolysis of sucrose

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