General Chemistry I — 2015 Past Questions

University of Ilorin CHM101: 155 questions.

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

1. Which of these pairs of metals has variable valencies?
   1. Zinc and caesium
   2. Iron and strontium
   3. Barium and scandium
   4. Iron and copper
2. J.J. Thomson's model of the atom was replaced by:
   1. Dalton's theory
   2. Rutherford Nuclear model
   3. Bohr model
   4. Balmer series model
3. Phosphorus burns as: P₄ + 5O₂ → P₄O₁₀. How many litres of O₂ at STP are needed to oxidize 12.4g of P₄? (P=31, O=16, molar volume=22.4L)
   1. 5.20 L
   2. 11.20 L
   3. 2.24 L
   4. 20.20 L
4. Which statement is FALSE when ice cubes are added to hot tea?
   1. Tea surrounds the ice cubes
   2. The system is the ice cubes
   3. Heat transfers from tea to ice, melting ice
   4. Heat only transfers from ice to tea, melting ice
5. Temperature, enthalpy, entropy, and energy changes are called:
   1. Non-state functions
   2. State functions
   3. Adiabatic functions
   4. Repulsive forces
6. Ionization energy:
   1. Increases across periods but decreases down groups
   2. Decreases across periods but increases down groups
   3. Increases both across periods and down groups
   4. None of the above
7. For the cell Pt|H₂(g,1atm)|H⁺(aq,1M)||Hg²⁺(aq,1M)|Hg(l); E°cell=0.851V. Determine E° for Hg²⁺/Hg.
   1. +0.851V
   2. -0.851V
   3. +1.702V
   4. -1.702V
8. Magnesium (atomic number=12) nucleus contains:
   1. 6 protons and 6 neutrons
   2. 6 neutrons and 6 electrons
   3. 12 neutrons and no protons
   4. 12 protons and no electrons
9. For A ⇌ B + C (K=2.0×10⁻⁵⁰), which is true?
   1. Forward reaction rate > backward rate
   2. Backward reaction rate > forward rate
   3. Higher concentration of A
   4. Higher concentration of B
10. Equilibrium of an exothermic reaction can be shifted forward by:
    1. Increasing temperature at constant pressure
    2. Warming up the apparatus
    3. Decreasing temperature at constant pressure
    4. Decreasing pressure at constant temperature
11. Which of the following is not one of Dalton's laws?
    1. Atoms are indestructible
    2. Atoms of the same element have isotopes with different masses
    3. Atoms of different elements have different chemical and physical properties
    4. All of these are examples of Dalton's laws
12. Element X has 19 electrons and forms an oxide. Which statement about its oxide is NOT true?
    1. When exposed to air, it slowly changes to liquid
    2. Its solution in water conducts electricity
    3. Its solution in water on evaporation gives a white solid
    4. Its oxide, when strongly heated, regenerates the element X
13. How many moles of hydrogen atoms are in 500mg of vitamin C (C₆H₈O₆)? (C=12.0, H=1.0, O=16.0)
    1. 2.01 × 10⁻² moles
    2. 2.27 × 10⁻² moles
    3. 1.20 × 10⁻² moles
    4. 3.07 × 10⁻² moles
14. What mass of oxygen contains the same number of atoms as 18.29g of chlorine? (Cl=35.5, O=16.0)
    1. 8.14g
    2. 8.24g
    3. 4.14g
    4. 2.24g
15. Which technique is useful for studying solid crystalline structure?
    1. X-ray fluorescence
    2. X-ray diffraction
    3. Atomic Absorption Spectrometry
    4. UV/Visible Spectrometry
16. For the exothermic reaction 2SO₂(g) + O₂(g) ⇌ 2SO₃(g), if temperature is reduced from 800°C to 500°C:
    1. The rate of reaction increases
    2. Concentration of SO₃ decreases
    3. Concentration of SO₃ increases
    4. SO₂ gas becomes unreactive
17. A good drying agent should be:
    1. Effervescent
    2. Hygroscopic
    3. Efflorescent
    4. Deliquescent
18. Given chlorine's mean atomic mass (35.5) with isotopes ³⁵Cl and ³⁷Cl, what is % of ³⁵Cl?
    1. 20
    2. 25
    3. 50
    4. 75
19. If 60cm³ of gas is heated from 27°C to 50°C at constant pressure, what is its new volume?
    1. 32.4dm³
    2. 55.7cm³
    3. 111.1cm³
    4. 64.6cm³
20. Electron affinity can be correctly represented by:
    1. M(g) + e⁻ → M⁻(g)
    2. M(g) + 2e⁻ → M⁻(g)
    3. M(g) + e⁻ → 2M⁻(g)
    4. M(g) + e⁻ → M²⁻(g)
21. The basic assumptions in the kinetic theory of gases that the collisions of the gaseous molecules are perfectly elastic implies that the:
    1. forces of attraction and repulsion are in equilibrium
    2. gaseous molecules can occupy any available space
    3. gaseous molecules will continue their motion indefinitely
    4. gases can be compressed
22. Which of these is not true of element of atomic number 23?
    1. It has 4 electronic shells
    2. It is in group 3
    3. It is a p-block element
    4. It forms acidic oxide
23. For the reaction H₂O₂(aq) + 2Br⁻(aq) + 2H⁺(aq) → Br₂(aq) + 2H₂O(aq), the rate law is Rate = k[H⁺][H₂O₂][Br⁻]. Determine the units of the rate constant.
    1. mol dm⁻³
    2. mol dm⁻³ time⁻¹
    3. mol⁻¹ dm³ time⁻¹
    4. mol⁻² dm⁶ time⁻¹
24. An element X has two isotopes ²⁰₁₀X and ²²₁₀X present in the ratio 1:3. The relative atomic mass of X would be:
    1. 20.5
    2. 21.0
    3. 21.5
    4. 22.5
25. An electron can move from one orbital to another and in so doing can:
    1. excite ground state energy levels
    2. absorb a quanta of energy
    3. emit a quanta of energy
    4. all of the above
26. Which of the following statements is an exception in the assumptions of the kinetic theory of gases?
    1. Gases are composed of many elastic particles
    2. The particles are of negligible size
    3. The particles are in constant random motion
    4. The particles are of negligible mass
27. How many grams of KClO₃ are needed to produce 10³ atoms of oxygen? (K = 39.0, Cl = 35.5)
    1. 3.70 × 10⁻¹⁷ g
    2. 3.70 × 10⁻²⁰ g
    3. 6.79 × 10⁻²⁰ g
    4. 2.70 × 10⁻¹⁷ g
28. How many quantum numbers are needed to describe the energy state of an electron in an atom?
    1. 1
    2. 2
    3. 3
    4. 4
29. Which of the following substances is not a homogeneous mixture?
    1. filtered sea water
    2. writing ink
    3. flood water
    4. soft drink
30. An increase in temperature causes an increase in the pressure of a gas at fixed volume due to an increase in the:
    1. number of molecules of the gas
    2. density of the gas molecules
    3. number of collisions between the gas molecules and the wall of the container
    4. number of collisions between the gas molecules
31. An element X forms the following compounds with chlorine: XCl₄, XCl₃, XCl₂. This illustrates the:
    1. law of multiple proportions
    2. law of chemical proportions
    3. law of simple proportions
    4. law of conservation of mass
32. If 1.0 dm³ of gas X diffuses through a porous plug in 60 seconds, while the same volume of hydrogen diffuses in 15 seconds under the same conditions, calculate the relative molecular mass of X (H = 1.0).
    1. 8.0
    2. 16.0
    3. 4.0
    4. 32.0
33. Stoichiometry involves the following except:
    1. Basis of qualitative analysis
    2. Calculation of yields
    3. Efficiency of chemical reaction
    4. Stoichiometric equation
34. The atomic numbers of elements X and Y are 12 and 9 respectively. The bond in their compound is:
    1. ionic
    2. covalent
    3. neutral
    4. coordinate
35. The component of atom that contributes least to its mass is the
    1. nucleus
    2. neutron
    3. electron
    4. proton
36. Which of these describes the spin on the last electron in Nitrogen with atomic number seven?
    1. +1/2
    2. -1/2
    3. 1/2
    4. 1
37. Any spontaneous change that occurs in the universe must be accompanied by an increase in the entropy of the universe is termed
    1. First law of thermodynamic
    2. Second law of thermodynamic
    3. Third law of thermodynamic
    4. Law of conservation of entropy
38. Which of the following atoms has the smallest radius?
    1. O
    2. F
    3. Ne
    4. N
39. Which of the following is a measure of the average kinetic energy of substance?
    1. volume
    2. mass
    3. pressure
    4. temperature
40. Which one of the following elements possesses complete filling of electrons in the d-orbital?
    1. Cu
    2. Ti
    3. Zn
    4. Co
41. How many moles of sulphur molecules are contained in 80.3g of sulphur if the molecular formula is S₈? (S = 32.06)
    1. 0.08 mole
    2. 0.16 mole
    3. 0.313 mole
    4. 0.260 g
42. Sodium and Potassium belong to the same group of the periodic table. This is because
    1. both are metals
    2. both are soft and lighter than water
    3. both form cations by loosing electrons
    4. both have identical electronic configuration
43. Metals are electropositive because
    1. they form positively charged ions
    2. they are electron acceptors
    3. they form negatively charged ions
    4. they form positively charged ions by losing electrons
44. Given that 2R (g) → 2P (g) + Q(g) ΔH = -x kJ. Which of the following conditions has no effect on the equilibrium position?
    1. Reducing the pressure
    2. Increasing the temperature
    3. adding more of Q
    4. Adding a catalyst
45. An ion with 5 protons, 6 neutrons and a charge of 3+ has an atomic number of
    1. 5
    2. 6
    3. 8
    4. 11
46. An element Z contained 90% ¹⁶Z and 10% ¹⁸Z, its relative atomic mass is
    1. 16.0
    2. 16.2
    3. 17.0
    4. 17.8
47. If a volume of a given mass of gas at 298K and a pressure of 205.2 × 10³ Nm⁻² is 2.12dm³. What is the volume of the gas at s.t.p?
    1. 39.3dm³
    2. 22.4dm³
    3. 4.93dm³
    4. 3.93dm³
48. The study of the rates and factors affecting rates of chemical reactions, and the determination of the mechanism by which reactions occur is known as
    1. chemical reactivity
    2. rate laws
    3. chemical kinetics
    4. reaction mechanism
49. Calculate the mass of HgO needed to produce 0.12 mole of mercury upon complete decomposition? (Hg = 200.59, O = 16.0)
    1. 11g
    2. 22g
    3. 26g
    4. 32g
50. Complete and balance the equation below, hence determine the values of x,y,z? P₄ + xO₂ + yH₂O → zH₃PO₄
    1. x,y,z = 5,3,4
    2. x,y,z = 5,6,4
    3. x,y,z = 2,6,3
    4. x,y,z = 5,6,2
51. Which of these compounds is not a molecular crystal?
    1. CO₂ (dry ice)
    2. H₂O (ice)
    3. CaCO₃ (limestone)
    4. I₂ (solid)
52. In which of the following reactions will a decrease in pressure and an increase in temperature shift the equilibrium to the right?
    1. A₂(g) + B₂(g) ⇌ Z₂(g) ΔH is -ve
    2. 2A₂(g) + 2B₂(g) ⇌ 3Z₂(g) ΔH is +ve
    3. A₂(g) + B₂(g) ⇌ 2Z₂(g) ΔH is –ve
    4. A₂(g) + B₂(g) ⇌ 3Z₂(g) ΔH is +ve
53. Which symbols represent atoms that are isotopes?
    1. ¹⁴C and ¹⁴N
    2. ¹⁶O and ¹⁸O
    3. ¹³¹I and ¹³¹I
    4. ²²²Rn and ³²²Rn
54. Which of the following halides has the highest entropy?
    1. HBr
    2. HF
    3. HI
    4. HCl
55. Atoms of element X (outermost electron of 2) combines with atoms of Y (outermost electrons of 7). Which of these statement is FALSE? The compound formed
    1. has formula XY
    2. is likely to be ionic
    3. contains X²⁻ ions
    4. contains Y⁻ ions
56. Calculate the percentage composition of each of the element in nitrogen trifluoride NF₃ (N = 14.0, F = 19.0)
    1. 19.7% N, 80.3% F
    2. 20.3% N, 79.7% F
    3. 11.9% N, 88.1% F
    4. 29.1% N, 70.9% F
57. For the cell Pt/H₂(g,1atm)/2H⁺(aq,1M)/Hg²⁺(aq,1M)/Hg(l), write down the spontaneous cell reaction
    1. H₂(g) + Hg²⁺(aq) → 2H⁺(aq) + Hg(l)
    2. 2H⁺(aq) + Hg(l) → H₂(g) + Hg²⁺(aq)
    3. H⁺(aq) + Hg(l) → ½H₂(g) + Hg²⁺(aq)
    4. ½H₂(g) + Hg²⁺(aq) → H⁺(aq) + Hg(l)
58. The necessary conditions for spontaneity for a redox reaction are
    1. E°cell < 0 and ΔG° > 0
    2. E°cell < 0 and ΔG° < 0
    3. E°cell > 0 and ΔG° > 0
    4. E°cell > 0 and ΔG° < 0
59. How many sub-orbitals are there in the f orbital of an atom?
    1. 12
    2. 9
    3. 7
    4. 5
60. An element X has two isotopes ²⁰X and ²²X present in the ratio 1:3. The relative atomic mass of X would be
    1. 20.5
    2. 21.0
    3. 21.5
    4. 22.5
61. If X(g) + B(g) → 2C(g) took place in 0.5 litre container, the no of moles of each material present at equilibrium are X - 1.0 mole, B - 2.0 moles and C - 3.0 moles the value of Kc is
    1. 4.5
    2. 6
    3. 9
    4. 18
62. Which of these elements has the highest ionization energy? (Li, B, N, Al)
    1. Li
    2. Al
    3. N
    4. B
63. How many moles of C₂H₂ are needed to produce 22g of CO₂ when C₂H₂ is burned? (C = 12.0, O = 16.0)
    1. 0.35 moles
    2. 0.25 moles
    3. 1.25 moles
    4. 1.35 moles
64. What is the name given to the energy change accompanying the addition of an electron to a gaseous atom?
    1. Ionization energy
    2. Electron affinity
    3. Ionization potential
    4. Electronegativity
65. The theory that electrons are situated in particular energy levels at specific distances away from the nucleus is by
    1. John Dalton
    2. Niels Bohr
    3. Ernest Rutherford
    4. R. A. Millikan
66. ΔG at equilibrium is
    1. Positive
    2. Negative
    3. 0
    4. None of the options
67. A mixture whose composition differs from point to point or from one property to another is termed
    1. Homogeneous mixture
    2. Heterogeneous mixture
    3. Composite mixture
    4. Colloidal mixture
68. Which of the following term indicated the number of bonds that can be formed by an atom?
    1. Oxidation number
    2. Valence
    3. Atomic number
    4. Electronegativity
69. If the temperature at which the solid is formed is approached slowly so as to allow the array of particles to become well ordered, then this will give rise to the formation of
    1. Amorphous solid
    2. Crystalline solid
    3. Particles
    4. Flat planes
70. At a constant pressure of 101 kPa, an ideal gas expands isothermally from 2.55 dm³ to 13.45 dm³, calculate the corresponding work for this process.
    1. 1100.9 J
    2. 1100.9 Nm
    3. 1000.9 J
    4. 1000.9 Nm
71. Screening effect is a factor of
    1. decreasing number of shells down the group
    2. equal number of shell across the period
    3. increase number of shell across the period
    4. increase number of shell down the group
72. The discovery of the neutrons could be attributed to
    1. Albert Einstein
    2. Ernest Rutherford
    3. Peter Curie
    4. J.J. Thomson
73. How many atoms are there in a 20.0g sample of silver? (Ag = 108g/mole)
    1. 3.11 × 10²³ atoms
    2. 4.21 × 10²³ atoms
    3. 2.21 × 10²³ atoms
    4. 1.11 × 10²³ atoms
74. How many electrons are in the L-shell of ³¹P?
    1. 2
    2. 5
    3. 8
    4. 18
75. Elements combine in fixed mass ratios to form compounds. This must mean that elements
    1. are made up of continuous matter without subunits
    2. are composed of discrete units called atoms
    3. have unambiguous atomic number
    4. are always chemically active
76. An equilibrium reaction with maximum yield of product will have
    1. ΔH - TΔS is zero
    2. ΔS is zero
    3. Equilibrium constant K very large
    4. Free energy change is zero
77. Cathode rays cause an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays
    1. are positively charged
    2. are negatively charged
    3. have mass
    4. travel in straight lines
78. The enthalpy change for melting 1 mole of a solid substance at 1 atm pressure is called the standard molar enthalpy of
    1. combustion
    2. freezing
    3. fusion
    4. vaporization
79. A boundary that does not permit the flow of heat is called
    1. adiabatic wall
    2. adiabatic
    3. closed system
    4. isolated system
80. Which of these atoms has the largest radius? (V, Cr, Mo, Cu)
    1. V
    2. Cr
    3. Mo
    4. Cu
81. The following factors affect the ionization energies of chemical elements EXCEPT
    1. nuclear pull
    2. atomic radius
    3. ionic size
    4. electron affinity
82. At equilibrium A(g) + B(g) ⇌ 3C(s) + D(g) ΔH is –ve, Yield of C will increase by
    1. decreasing the pressure on the reaction mixture
    2. using a larger closed vessel
    3. increasing the temperature
    4. removing some D
83. Who devised the means of assigning atomic number to elements?
    1. Chadwick
    2. Geiger and Marsden
    3. Bohr
    4. Moseley
84. What type of bond(s) hold graphite together?
    1. network of electrovalent bonds
    2. network of covalent bonds
    3. network of dative bonds
    4. network of internuclear forces
85. Which of the following terms define electronegative elements?
    1. electron donor
    2. electron acceptor
    3. positively charged ion
    4. none of the above
86. What are the elements which occur between the alkaline earth metals and the boron family in periods 4-6?
    1. transition metals
    2. representative elements
    3. s-block elements
    4. all of the above
87. For a change in pressure to affect a chemical system at equilibrium, which statement is NOT correct?
    1. Both the reactant and the product must be gaseous
    2. Product or Reactant must be gaseous
    3. The total number of gaseous molecules on both sides must be different
    4. None of the above
88. Elements P,Q,R,S have 6,11,15 and 17 electrons respectively, therefore
    1. P will form an electrovalent bond with R
    2. Q will form a covalent bond with S
    3. R will form an electrovalent bond with S
    4. Q will form an electrovalent bond with S
89. In equilibrium reaction, K = 1×10⁻³ means
    1. the concentration of reaction and that of the product are almost equal
    2. reaction goes very little to product
    3. rate of reaction is very slow
    4. reaction proceeds with virtually no reactant left
90. Element in the same group in the periodic table have the same
    1. Number of valence electrons
    2. Number of shells
    3. Atomic Number
    4. Electronic configuration
91. Compared to the charge and mass of a proton, an electron has
    1. The same charge and a smaller mass
    2. The same charge and the same mass
    3. An opposite charge and a smaller mass
    4. An opposite charge and the same mass
92. In which reaction would you expect the product to be more stable at higher pressure?
    1. N₂(g) + O₂(g) → 2NO(g)
    2. N₂O₄(g) → 2NO₂(g)
    3. 2SO₂(g) + O₂(g) → 2SO₃(g)
    4. PCl₅(g) → PCl₃(g) + Cl₂(g)
93. How many principal electronic shells has an atom with configuration 1s² 2s² 2p⁶ 3s²?
    1. 3
    2. 4
    3. 6
    4. 12
94. A beryllium atom has 4 protons, 5 neutrons and 4 electrons. What is the mass number of this atom?
    1. 4
    2. 5
    3. 8
    4. 9
95. In the periodic table, the past arrangement was based on
    1. Atomic masses
    2. Mass number
    3. Atomic number
    4. Valence electron
96. Calculate the number of moles of KMnO₄ that are present in 15.8g of KMnO₄? (K = 39.0, Mn = 54.9, O = 16.0)
    1. 0.10 mole
    2. 0.02 mole
    3. 0.20 mole
    4. 0.05 mole
97. A mixture of H₂(g) and O₂(g) at room temperature will not react together to form any product. But at 700°C these gases react instantly to form product why?
    1. at 700°C the gaseous molecules are highly energetic
    2. at 700°C the intramolecular forces are overcome
    3. at 700°C the molecular collisions overcome the activation energy
    4. none of the above
98. An electron in the ground state of the Bohr atom has a radius of 0.053 nm. What is the first excited state?
    1. 0.053 nm
    2. 0.106 nm
    3. 0.159 nm
    4. 0.212 nm
99. How many moles of C₂H₂ are needed to produce 44g of CO₂ when C₂H₂ is burned (C = 12.01, H = 1.01)
    1. 0.30 moles
    2. 0.25 moles
    3. 0.50 moles
    4. 0.75 moles
100. Which of the following statements is FALSE about isotopes of the same element?
     1. They have the same no of electron in their outer most shell
     2. They have different atomic masses
     3. They have the same atomic no and the same no of electrons
     4. They have the same no of atoms but different no of electrons

Register free to unlock all 155 questions with answers and explanations