General Chemistry I — 2026-exam Past Questions

University of Ilorin CHM101: 378 questions.

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

  1. Which of the following can be used as a reference electrode?
    1. Ion electrode
    2. Silver–silver chloride electrode
    3. Glass membrane electrode
    4. Electron electrode
  2. Na₂CO₃(s) → Na₂CO₃(aq), ΔH = x kJ mol⁻¹. ΔH represents:
    1. Enthalpy of dissolution
    2. Enthalpy of hydration
    3. Enthalpy of neutralization
    4. Enthalpy of combustion
  3. What type of bond exists in N₂ and O₂?
    1. Ionic
    2. Covalent
    3. Hydrogen
    4. Metallic
  4. Aluminium sulphate reacts with calcium hydroxide to produce aluminium hydroxide and calcium sulphate: Al₂(SO₄)₃ + Ca(OH)₂ → Al(OH)₃ + CaSO₄. Find the coefficient of Ca(OH)₂ after balancing.
    1. 1
    2. 3
    3. 6
    4. 12
  5. When the difference in electronegativity is high, the compound formed is most likely:
    1. Ionic
    2. Covalent
    3. Metallic
    4. Coordinate
  6. What is the coefficient of CO in the balanced chemical equation: Fe₂O₃ + CO → Fe + CO₂?
    1. 1
    2. 2
    3. 3
    4. 4
  7. Arrange the following hydrogen halides in order of increasing polarity:
    1. HF < HCl < HBr < HI
    2. HI < HBr < HCl < HF
    3. HCl < HF < HBr < HI
    4. HBr < HI < HF < HCl
  8. Which of the following is the weakest acid?
    1. HI
    2. HBr
    3. HCl
    4. HF
  9. Which of the following will increase the rate of diffusion of a gas?
    1. Increase in temperature
    2. Decrease in temperature
    3. Increase in density
    4. Increase in molar mass
  10. Which of the following gases will diffuse fastest?
    1. H₂
    2. O₂
    3. CO₂
    4. N₂
  11. The function of a breeder reactor is:
    1. To reduce radioactive waste
    2. To increase the amount of fissionable material
    3. To slow down nuclear reactions
    4. To absorb neutrons
  12. The rate of diffusion of a gas depends mainly on its:
    1. Temperature
    2. Pressure
    3. Density
    4. Colour
  13. Radioactive series are classified according to mass number based on:
    1. Modulo 2
    2. Modulo 3
    3. Modulo 4
    4. Modulo 5
  14. Which of the following gases diffuses fastest?
    1. CO₂
    2. H₂
    3. CH₄
    4. O₂
  15. In an endothermic reaction, an increase in temperature will cause the equilibrium to shift:
    1. Forward
    2. Backward
    3. Unchanged
    4. To completion
  16. The half-life of a radioactive substance is:
    1. Independent of the initial quantity
    2. Dependent on pressure
    3. Dependent on temperature
    4. Dependent on initial quantity
  17. The Bohr model explains the emission spectra of:
    1. All elements
    2. Only hydrogen
    3. All alkali metals
    4. Multi-electron atoms
  18. The mass of a gas occupying 1 L at STP is 1.16 g. If the molar volume of the gas at STP is 22.4 L, identify the gas.
    1. H₂
    2. NH₃
    3. C₂H₂
    4. HCl
  19. Which of the following gases occupies the largest volume for the same number of moles at the same temperature and pressure?
    1. H₂
    2. O₂
    3. CH₄
    4. They all occupy equal volumes
  20. The enthalpy of neutralization is the same as the heat of:
    1. Atomization of acid
    2. Formation of acid
    3. Dissolution of salt
    4. Reaction between an acid and a base
  21. The three unpaired electrons in a nitrogen atom have which direction of spin?
    1. Same
    2. Different
    3. Alternating
    4. Opposite
  22. Which of the following is not non-polar covalent?
    1. CH₄
    2. H₂
    3. I₂
    4. None of these
  23. The formula of ammonium sulphate is:
    1. (NH₄)₂SO₄
    2. NH₄SO₄
    3. (NH₄)SO₄
    4. NH₄(SO₄)₂
  24. Which of the following is the most ionic?
    1. LiF
    2. CsF
    3. KF
    4. NaF
  25. Which of the following oxoacids is the weakest?
    1. HClO₃
    2. HClO
    3. HClO₂
    4. HClO₄
  26. Which of the following is a weak acid?
    1. HI
    2. HF
    3. HBr
    4. HCl
  27. The percentage composition of oxygen in Ca(NO₃)₂ is: (Ca = 40, N = 14, O = 16)
    1. 48.8%
    2. 58.5%
    3. 60.0%
    4. 65.9%
  28. The number of atoms in 12 g of carbon is: (C = 12)
    1. 6.02 × 10²³
    2. 3.01 × 10²³
    3. 1.20 × 10²⁴
    4. 12 × 10²³
  29. The number of atoms in 0.5 moles of helium is:
    1. 3.01 × 10²³
    2. 6.02 × 10²³
    3. 1.20 × 10²⁴
    4. 0.5 × 10²³
  30. The decay constant of a radioactive isotope is 2 × 10⁻³ day⁻¹. Its half-life is:
    1. 173 days
    2. 346.5 days
    3. 693 days
    4. 1000 days
  31. Which of the following gases occupies the largest volume at constant temperature and pressure for one mole?
    1. CH₄
    2. O₂
    3. H₂
    4. They all occupy equal volumes
  32. Which quantum number is responsible for identifying the Pₓ, Pᵧ and P_z orbitals?
    1. Magnetic quantum number
    2. Azimuthal quantum number
    3. Principal quantum number
    4. Spin quantum number
  33. Electrons in the same orbital have different:
    1. m
    2. s
    3. l
    4. n
  34. Balance the redox reaction in acidic medium: NO₃⁻ + H₂O₂ → NO₂ + O₂
    1. 2NO₃⁻ + H₂O₂ + 2H⁺ → 2NO₂ + O₂ + 2H₂O
    2. NO₃⁻ + H₂O₂ → NO₂ + O₂ + H₂O
    3. 2NO₃⁻ + H₂O₂ → 2NO₂ + 2O₂
    4. NO₃⁻ + 2H₂O₂ → NO₂ + 2O₂ + H₂O
  35. The number of possible values of the magnetic quantum number (m) is given by:
    1. 2l + 2
    2. 2l
    3. 2l + 1
    4. 2n²
  36. The following processes are endothermic except:
    1. Boiling of water
    2. Melting of ice
    3. Condensation
    4. Evaporation
  37. Saturated vapour pressure is defined as:
    1. Vapour pressure at equilibrium
    2. Maximum atmospheric pressure
    3. Pressure of dry gas
    4. External pressure on liquid
  38. Which of the following always has a negative ΔH?
    1. Combustion
    2. Dissolution of ionic compounds
    3. Dilution of solution
    4. Evaporation
  39. If the electrode potential of a cell is zero, it indicates that:
    1. The system is at equilibrium
    2. The reaction has stopped permanently
    3. The reaction is spontaneous
    4. The reaction is irreversible
  40. The double vertical line in a cell notation represents:
    1. Salt bridge
    2. Electrode
    3. Phase boundary
    4. External circuit
  41. 3.7 × 10¹⁰ disintegrations per second (dps) is equal to:
    1. 1 Ci
    2. 0.01 Ci
    3. 0.001 Ci
    4. 10 Ci
  42. Who discovered radioactivity in 1896?
    1. Henri Becquerel
    2. Julius Lothar Meyer
    3. Ernest Rutherford
    4. Marie Curie
  43. The SI unit of radioactivity is:
    1. Curie
    2. Becquerel
    3. Gray
    4. Sievert
  44. Californium-252 decays mainly by:
    1. Alpha emission and spontaneous fission
    2. Beta minus emission only
    3. Gamma emission only
    4. Electron capture
  45. Equal volumes of all gases at the same temperature and pressure contain:
    1. Equal number of molecules
    2. Equal masses
    3. Equal densities
    4. Equal molar masses
  46. Which of the following uses electricity to drive a non-spontaneous reaction?
    1. Galvanic cell
    2. Electrolytic cell
    3. Fuel cell
    4. Concentration cell
  47. For the reaction H₂ + Cl₂ → 2HCl, the bond enthalpies given are H–H = 285 kJ mol⁻¹, Cl–Cl = 436 kJ mol⁻¹ and H–Cl = 425 kJ mol⁻¹. Calculate the enthalpy change of the reaction.
    1. −129 kJ
    2. +129 kJ
    3. −169 kJ
    4. +169 kJ
  48. What is the formula of a compound formed between an element in Group III and an element in Group V?
    1. MX
    2. M₂X₂
    3. M₃X₂
    4. M₂X₃
  49. Balance the reaction C₂H₆ + O₂ → CO₂ + H₂O. Find the sum of the coefficients in the balanced equation.
    1. 13
    2. 15
    3. 19
    4. 21
  50. AgNO₃ + NaCl → AgCl + NaNO₃. Which of the following is correct?
    1. All the coefficients are 1
    2. The coefficient of NaNO₃ is 2
    3. The coefficient of AgCl is 2
    4. The equation is not balanced
  51. A zero-order reaction has a rate constant of 2 × 10⁻² mol L⁻¹ s⁻¹. After 25 s the concentration is 0.5 M. Calculate the initial concentration.
    1. 0.1 M
    2. 1 M
    3. 0.01 M
    4. 0.001 M
  52. As the electron is moved away from the nucleus in the Bohr model, its energy:
    1. Increases
    2. Decreases
    3. Remains the same
    4. Becomes zero
  53. Fe₂O₃ + CO → Fe + CO₂. What is the coefficient of CO?
    1. 1
    2. 2
    3. 3
    4. 4
  54. Which of the following has no effect on the direction of equilibrium?
    1. Temperature
    2. Pressure
    3. Concentration
    4. Catalyst
  55. The temperature of an endothermic reaction at equilibrium is increased. What happens?
    1. It shifts forward
    2. It shifts backward
    3. No change
    4. The reaction stops
  56. What is the heat of a system when temperature and pressure are kept constant?
    1. Enthalpy
    2. Entropy
    3. Internal energy
    4. Free energy
  57. Which of the following is true of condensation?
    1. It happens at boiling point and at atmospheric pressure
    2. It happens below boiling point and at atmospheric pressure
    3. It happens at melting point and atmospheric pressure
    4. It happens only at absolute zero
  58. The e/m (charge-to-mass ratio) of an electron was determined by:
    1. R. A. Millikan
    2. J. J. Thomson
    3. Ernest Rutherford
    4. John Dalton
  59. Which of the following is true of the rate of a zero-order reaction?
    1. The rate is constant and independent of time and concentration
    2. The rate increases with time
    3. The rate decreases with time
    4. The rate is directly proportional to concentration
  60. Every spontaneous reaction occurs with:
    1. Decrease in the entropy of the universe
    2. Increase in the entropy of the universe
    3. No change in entropy
    4. Decrease in enthalpy
  61. Esterification reaction is what type of equilibrium?
    1. Liquid phase homogeneous
    2. Heterogeneous
    3. Ionic
    4. Dynamic
  62. C₂H₆ → 2C + 6H, ΔH = +2822.7 kJ. Given C–H = +415 kJ, find the C–C bond energy.
    1. 332.7 kJ
    2. 665.4 kJ
    3. 116.5 kJ
    4. 445.2 kJ
  63. Which of the following equilibrium constants is applicable to an esterification reaction?
    1. Kc and Kp
    2. Kc only
    3. Kp only
    4. Ke
  64. Propane reacts with oxygen: C₃H₈ + O₂ → CO₂ + H₂O. Find the coefficient of oxygen.
    1. 6
    2. 5
    3. 4
    4. 3
  65. Which of the following equilibrium constants is only applicable to gases?
    1. Kc
    2. Kp
    3. Ke
    4. Kw
  66. What is the effect of a catalyst on equilibrium?
    1. It affects the rate at which equilibrium is attained
    2. It affects the equilibrium position
    3. It changes the equilibrium constant
    4. It increases the yield of products
  67. Balance the redox reaction: BrO₃⁻ + Fe²⁺ → Fe³⁺ + Br⁻
    1. BrO₃⁻ + 6Fe²⁺ + 6H⁺ → Br⁻ + 6Fe³⁺ + 3H₂O
    2. BrO₃⁻ + 3Fe²⁺ → Br⁻ + 3Fe³⁺
    3. BrO₃⁻ + Fe²⁺ + 3H₂O → Br⁻ + Fe³⁺
    4. BrO₃⁻ + 6Fe³⁺ → Br⁻ + 6Fe²⁺
  68. Find the rate constant of a radioactive reaction with a half-life of 1575 years.
    1. 4.40 × 10⁻⁴ yr⁻¹
    2. 6.93 × 10⁻³ yr⁻¹
    3. 1.14 × 10⁻³ yr⁻¹
    4. 9.80 × 10⁻⁵ yr⁻¹
  69. Find the decay constant of a radioactive element with a half-life of 3.382 days.
    1. 0.205 day⁻¹
    2. 0.048 day⁻¹
    3. 2.05 day⁻¹
    4. 0.693 day⁻¹
  70. The process in which a gas changes directly to a solid is known as:
    1. Sublimation
    2. Condensation
    3. Deposition
    4. Freezing
  71. The standard electrode potential of hydrogen is:
    1. +1.00 V
    2. 0.00 V
    3. −1.00 V
    4. +0.34 V
  72. Which gas will diffuse fastest under normal conditions?
    1. Hydrogen gas
    2. Carbon dioxide
    3. Nitrogen gas
    4. Oxygen gas
  73. Find the number of moles of carbon present in 1.204 × 10²⁴ atoms.
    1. 2.00 mol
    2. 1.00 mol
    3. 0.50 mol
    4. 3.00 mol
  74. Find the partial pressure of oxygen in a gaseous mixture containing 8 g of O₂ and 14 g of N₂ if the total pressure is 750 mmHg.
    1. 300 mmHg
    2. 250 mmHg
    3. 450 mmHg
    4. 525 mmHg
  75. The mass of 0.5 moles of CaCO₃ is: (Ca = 40, C = 12, O = 16)
    1. 25 g
    2. 50 g
    3. 75 g
    4. 100 g
  76. What is the process in which a gas changes to plasma?
    1. Recombination
    2. Ionization
    3. Melting
    4. Sublimation
  77. The mass of 0.5 moles of C₆H₁₂O₆ is: (C = 12, H = 1, O = 16)
    1. 45 g
    2. 60 g
    3. 90 g
    4. 180 g
  78. When temperature and pressure are constant, heat content is equal to:
    1. Change in internal energy
    2. Change in enthalpy
    3. Change in entropy
    4. Change in free energy
  79. The reaction between a Group IIA element and a Group VA element gives which formula?
    1. MX₃
    2. M₂X₃
    3. M₃X₂
    4. M₃X
  80. In the decomposition CaCO₃ → CaO + CO₂, calculate the number of moles of CO₂ formed if 200 g of CaCO₃ is decomposed. (Ca = 40, C = 12, O = 16)
    1. 2
    2. 3
    3. 4
    4. 6
  81. Calculate the heat released when 12.5 g of H₂O is produced, given that the heat of combustion is −571.0 kJ per mole of H₂O formed. (H = 1, O = 16)
    1. −396.5 kJ
    2. −198.3 kJ
    3. −713.8 kJ
    4. −571.0 kJ
  82. If 1 mole of Mg reacts with 1 mole of chlorine molecules, the product is:
    1. MgCl₂, ionic
    2. MgCl₂, covalent
    3. Mg₂Cl, ionic
    4. Mg₂Cl, covalent
  83. If a catalyst is added to a reaction, what happens to the Gibbs free energy change (ΔG)?
    1. It increases
    2. It decreases
    3. It remains the same
    4. It becomes zero
  84. What will be the cell potential of an electrochemical cell if it is at equilibrium?
    1. 0
    2. > 0
    3. < 0
    4. 1
  85. The energy of a photon is represented by:
    1. E = hf/λ
    2. E = hc/λ
    3. E = hπ/c
    4. E = h²/λ
  86. The endothermic change when one mole of gaseous atoms is formed from its element is called:
    1. Heat of formation
    2. Heat of atomization
    3. Heat of vaporization
    4. Heat of sublimation
  87. A heterogeneous equilibrium contains:
    1. Liquid
    2. Solid
    3. One phase
    4. Two or more phases
  88. A 200 g sample of a compound absorbs 0.54 kJ of heat and its temperature rises by 25 K. Calculate the specific heat capacity of the compound in J/g·K.
    1. 0.108 J/g·K
    2. 1.8 × 10⁻⁴ J/g·K
    3. 1.8 × 10⁻³ J/g·K
    4. 0.432 J/g·K
  89. How many radial nodes are in a 2p orbital?
    1. 0
    2. 1
    3. 2
    4. 3
  90. Calculate the percentage by mass of water in CuSO₄·5H₂O. (Cu = 64, S = 32, O = 16, H = 1)
    1. 36.0%
    2. 25.4%
    3. 40.2%
    4. 18.0%
  91. What is the chemical formula for copper(II) sulphate pentahydrate?
    1. CuSO₄·5H₂O
    2. CuSO₄·2H₂O
    3. Cu₂SO₄·5H₂O
    4. CuSO₄·H₂O
  92. What is the name of (NH₄)₂SO₄?
    1. Ammonium sulphate
    2. Ammonia sulphide
    3. Ammonium sulphite
    4. Diammonium sulphate
  93. What is the most important condition for chemical equilibrium?
    1. The reaction must be in a closed system
    2. The reaction must happen fast
    3. The temperature must be constantly changing
    4. The concentration of products must be zero
  94. Who discovered artificial radioactivity?
    1. Irene and Frederic Joliot-Curie
    2. Ernest Rutherford
    3. Marie Curie
    4. Henri Becquerel
  95. For a cell with Cu²⁺ and Ni, the cell potential E° is 0.50 V. If E° for Cu is 0.34 V, find the E° for nickel.
    1. −0.16 V
    2. −0.76 V
    3. 0.84 V
    4. −0.25 V
  96. Find the molar mass of a gas where P = 1.1 atm, T = 30°C, R = 0.0821 L atm mol⁻¹ K⁻¹ and the density is 1.15 g/L.
    1. 25.0 g/mol
    2. 31.2 g/mol
    3. 26.1 g/mol
    4. 44.0 g/mol
  97. What represents the initial concentration in the half-life equation of a zero-order reaction?
    1. [A]₀
    2. [A]t
    3. k
    4. t½
  98. Graham's law is associated with:
    1. Temperature
    2. Pressure
    3. Concentration
    4. Density
  99. Which of the following represents a zero-order rate law?
    1. Rate = k[A]⁰[B]⁰
    2. Rate = k[A]¹[B]⁰
    3. Rate = k[A]¹[B]¹
    4. Rate = k[A]²
  100. 1.008 g of hydrogen is deposited when a quantity of electricity is passed for 2 hours. What mass of copper will be liberated from CuSO₄ by the same quantity of electricity? (Cu = 63.5)
    1. 31.75 g
    2. 63.5 g
    3. 15.8 g
    4. 127 g

Register free to unlock all 378 questions with answers and explanations

SmartDriller logo

SmartDriller

Loading your past questions, mock exams, notes, and video tutorials...

Starting up…