General Chemistry I — 2021 Past Questions

University of Ilorin CHM101: 50 questions.

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

1. A compound containing 81.76g of Fe and 34.97g of oxygen. If the vapor density of the compound is 80g/mol, calculate the molecular formula of the compound (Fe=56g, O=16g)
   1. FeO
   2. Fe₂O₃
   3. Fe₃O₄
   4. Fe₂O
2. A compound consisting of Boron and hydrogen contains 78.5714% of Boron, calculate the formula of the compound (B=11g, H=1g)
   1. BH
   2. BH₃
   3. B₂H₃
   4. BH₂
3. What is the ratio of the number of water molecules to ammonia in the balanced equation? Ba₃N₂ + H₂O → Ba(OH)₂ + NH₃
   1. 3:6
   2. 6:2
   3. 3:2
   4. 2:3
4. One Faraday of electricity will deposit how many moles of copper? Cu → Cu²⁺ + 2e⁻
   1. 1
   2. 2
   3. ½
   4. none of these
5. Mass of neutron is ------ times of electron
   1. none of these
   2. 1840
   3. 2340
   4. 2000
6. What is the unit of the rate constant of second order reaction?
   1. mol·L⁻¹·s⁻¹
   2. mol⁻¹·L·s⁻¹
   3. mol·L·s
   4. mol⁻¹·L⁻¹·s⁻¹
7. A+B → C; R = k[A]. Which of these is not correct?
   1. graph of [A] against t is linear
   2. the rate is dependent on [A]
   3. the rate is independent of [B]
   4. the unit of k is s⁻¹
8. The formula of the compound I₂O₅ is
   1. iodine pentoxide
   2. iodine pentaoxygen
   3. iodine pentahydroxyl
   4. diiodine pentoxide
9. Which of the following has the highest ionization enthalpy?
   1. carbon
   2. boron
   3. nitrogen
   4. oxygen
10. Calculate the change in internal energy if a system loses 50J of heat and 0.15kJ of work is done on it
    1. 100J
    2. 50J
    3. 200J
    4. 150J
11. The electron discovery was made by?
    1. J.J Thomson
    2. Ernest Rutherford
    3. James Chadwick
    4. Robert Millikan
12. Which of the following has the highest power of penetration?
    1. gamma
    2. alpha
    3. beta
    4. neutron
13. For what order of reaction is half-life increased if initial concentration is doubled?
    1. zero
    2. first
    3. second
    4. third
14. Which emission contains fast-moving electrons?
    1. gamma
    2. alpha
    3. beta
    4. proton
15. Calculate the time required for 75% decomposition of a second order reaction (initial conc. = 4.46M) if 50% decomposes in 32min.
    1. 48min
    2. 64min
    3. 96min
    4. 128min
16. Calculate the amount of copper (in grams) liberated by 0.5 Faradays (Cu=63.5g/mol).
    1. 15.875g
    2. 31.75g
    3. 63.5g
    4. 7.9375g
17. Calculate the number of particles in 48g of pentaoxovanadate(V) (V=51g/mol, O=16g/mol, NA=6.02×10²³).
    1. 1.59 × 10²³
    2. 3.01 × 10²³
    3. 6.02 × 10²³
    4. 12.04 × 10²³
18. The branch of science that studies energy transformation accompanying physical and chemical changes is called?
    1. Thermodynamics
    2. Kinetics
    3. Quantum mechanics
    4. Electrochemistry
19. The half-life of a first order reaction is 2.0×10⁴ s. How long will it take for the reaction to reach 60% completion?
    1. 440.7min
    2. 220.4min
    3. 880.1min
    4. 110.2min
20. The decomposition of dimethyl ether at 504°C is first order with half-life 1570s. Calculate the fraction of initial amount remaining after 4710s.
    1. ⅛
    2. ¼
    3. ½
    4. ⅙
21. Hess's law of constant heat summation states that:
    1. For any reaction written in steps, ΔH° is the sum of ΔH° for the steps
    2. Heat is conserved in chemical reactions
    3. Enthalpy is a state function
    4. Energy cannot be created or destroyed
22. Formula for Aluminum Trioxophosphate(III)
    1. AlPO₃
    2. Al₃PO₄
    3. Al(PO₃)₃
    4. Al₂(PO₄)₃
23. Mass number is made up of:
    1. Number of protons and neutrons
    2. Number of electrons and protons
    3. Number of neutrons and electrons
    4. Number of protons only
24. How many atoms are in 0.19g of Fluorine? (F=19g/mol, NA=6.02×10²³)
    1. 6.02 × 10²³
    2. 3.01 × 10²³
    3. 1.20 × 10²³
    4. 6.02 × 10²¹
25. A strip of Zinc is immersed in Copper sulfate. What’s the half-cell reaction?
    1. Zn|Zn²⁺ || Cu²⁺|Cu
    2. Cu|Cu²⁺ || Zn²⁺|Zn
    3. Zn²⁺|Zn || Cu|Cu²⁺
    4. Cu²⁺|Cu || Zn|Zn²⁺
26. Components in a nucleus are ________
    1. proton and neutron
    2. electron and proton
    3. neutron and electron
    4. proton only
27. Which of the following is isoelectronic to Ar?
    1. K⁺
    2. Cl⁻
    3. Both K⁺ and Cl⁻
    4. S²⁻
28. What is the unit for a zero-order reaction?
    1. M/s
    2. s⁻¹
    3. L·mol⁻¹·s⁻¹
    4. mol·L⁻¹·s⁻¹
29. What is the unit for a first-order reaction?
    1. s⁻¹
    2. M/s
    3. L·mol⁻¹·s⁻¹
    4. mol·L⁻¹·s⁻¹
30. At 34.1°C, the vapour pressure of water is 40.1 torr. What's the vapour pressure at 85.5°C if the heat of vaporization is 40.7 kJ/mol?
    1. 394.4 torr
    2. 200.5 torr
    3. 760.0 torr
    4. 100.0 torr
31. 0.14g of an oxide of carbon occupies 112 cm³ at STP. What's the IUPAC name of the oxide?
    1. Carbon monoxide
    2. Carbon dioxide
    3. Carbon trioxide
    4. Carbon suboxide
32. Which of the following is a member of Döbereiner's triads?
    1. Ca, Sr, Ba
    2. S, Se, Br
    3. C, Si, Ge
    4. Cl, Br, I
33. An exothermic ________ heat and has a ________ enthalpy.
    1. releases, negative
    2. absorbs, positive
    3. releases, positive
    4. absorbs, negative
34. A chemical reaction has the rate law r = [A][B]². What is its order?
    1. 1
    2. 2
    3. 3
    4. 0
35. Calculate the molar heat capacity of 100g of water if 836J of heat was added at 273K (H=1, O=16).
    1. 0.55 J/mol·K
    2. 4.18 J/mol·K
    3. 75.3 J/mol·K
    4. 1.00 J/mol·K
36. The element with atomic number 38 is in the same group as ________.
    1. Group 1
    2. Group 2
    3. Group 17
    4. Group 18
37. The unit of rate constant for a third-order reaction is ________.
    1. L²·mol⁻²·s⁻¹
    2. mol·L⁻¹·s⁻¹
    3. s⁻¹
    4. M/s
38. What is the heat of vaporization of water?
    1. 40.4 kJ/mol
    2. 6.01 kJ/mol
    3. 285.8 kJ/mol
    4. 100.0 kJ/mol
39. An element with atomic number 54 and mass number 132 has how many protons?
    1. 54
    2. 78
    3. 132
    4. 186
40. The graph of a zero-order reaction is always a straight line.
    1. Yes
    2. No
    3. Only at high temperatures
    4. Only for gases
41. Who discovered the electron?
    1. J.J. Thomson
    2. Ernest Rutherford
    3. James Chadwick
    4. Niels Bohr
42. What is the group of an element with atomic number 33?
    1. Group 15
    2. Group 16
    3. Group 13
    4. Group 17
43. What type of foil was used in Rutherford's experiment?
    1. Gold foil
    2. Aluminum foil
    3. Copper foil
    4. Silver foil
44. Which halide is liquid at room temperature?
    1. Bromine
    2. Chlorine
    3. Iodine
    4. Fluorine
45. What is the heat of sublimation of water?
    1. 46.7 kJ/mol
    2. 40.7 kJ/mol
    3. 6.01 kJ/mol
    4. 285.8 kJ/mol
46. A gas occupies 1.12 dm³ at STP. If the mass is 2.3g, what is the gas?
    1. Nitrogen dioxide
    2. Carbon dioxide
    3. Oxygen
    4. Hydrogen
47. Who discovered the proton?
    1. Ernest Rutherford
    2. J.J. Thomson
    3. James Chadwick
    4. Niels Bohr
48. Two electrons in the 1s orbital must have different spin quantum numbers to satisfy:
    1. Hund's rule
    2. the magnetic rule
    3. the Pauli Exclusion Principle
    4. the Aufbau principle
49. J.J. Thomson is known for his: I. 'Plum pudding' model of the atom II. Thin gold experiment III. Cathode ray experiment IV. Discovery of nucleus
    1. I and II are correct
    2. II and III are correct
    3. I and IV are correct
    4. I and III are correct
50. 50 cm³ of hydrogen are sparked with 20 cm³ of oxygen at 100°C and 1 atm. The total volume of residual gases is:
    1. 50 cm³
    2. 70 cm³
    3. 30 cm³
    4. 40 cm³

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