Chemistry Past Paper PDF

## Unit 4-5 MCQ 1. What is the molarity of a solution containing ClO3-(aq) if 15 mL of the solution in needed to react completely with 20 mL of 0.20 M MnO4- solution? 2H2O(l) + 4MnO4-(aq) + 3ClO3-(aq) → 4MnO2(s) + 3ClO4-(aq) + 4OH-(aq) A. 0.10 M B. 0.20 M C. 0.30 M D. 0.40 M 2. When the followin...

## Unit 4-5 MCQ 1. What is the molarity of a solution containing ClO3-(aq) if 15 mL of the solution in needed to react completely with 20 mL of 0.20 M MnO4- solution? 2H2O(l) + 4MnO4-(aq) + 3ClO3-(aq) → 4MnO2(s) + 3ClO4-(aq) + 4OH-(aq) A. 0.10 M B. 0.20 M C. 0.30 M D. 0.40 M 2. When the following half-reactions below are combined and balanced, the coefficient for the H2 will be: 2Al → Al3+ + 3e- 2H+ + 2e- → H2 A. 1 B. 2 C. 3 D. 4 3. In which of the following species is the oxidation state for nitrogen the greatest? A. NO B. NO2 C. NO2- D. NO3- 4. If the following reaction is determined to be second order overall, what are the units of the rate constant, k? A + B → C A. time-1 B. mol L-1 time-1 C. L mol-1 time-1 D. cannot determine the order and units of k without experimental data ## Questions 5 and 6 use the following information: Shown below are the initial concentrations for three different trials of the reaction 3X + Y → Z. **Trial 1:** Rate = 0.10 Ms-1 **Trial 2:** Rate = ? **Trial 3:** Rate = 0.10 Ms-1 5. If the reaction is determined to be first order in X, what will be the rate for trial 2? A. 0.10 Ms-1, because the rate constant of a specific reaction is constant at a given temperature B. 0.10 Ms-1, because Y is now a limiting reactant and adding more X can't increase the rate. C. 0.20 Ms-1, because doubling the concentration of X will double the rate. D. 0.60 Ms-1, because the coefficient of X in the balanced equation is 3 and the concentration of X is doubled, so 3x2=6. 6. What is the order of the reaction with respect to Y? A. 0 B. 1/2 C. 1 D. 2 7. What is the role of H3O+ in the mechanism shown below? CH3CH=CHCH3 + H3O+ ⇄ CH3CH2CHCH3 + H2O CH3CH2CHCH3 + H2O ⇄ CH3CH2CH=CH2 + H3O+ A. reactant B. catalyst C. inhibitor D. intermediate 8. Which of the following is the most likely sequence and orientation of the collisions of the reactants that would result in the overall reaction shown to the right? A. + B. + C. ++ D. ++ 9. An energy profile for a reaction is shown to the right. Which mechanism below correctly describes the process shown above? A. T + A → AT slow AT → Z fast B. AT → Z C. T + A → AT fast AT → Z slow D. T + A → AT fast AT + Z → ZAT slow ZAT → X fast 10. When methanol, CH3OH(l), is burned, the products are water and carbon dioxide. Use the reaction shown below to determine which of the following statements is correct. 2CH3OH(l) + 3O2(g) → 4H2O(l) + 6CO2(g) A. Methanol is being consumed at twice the rate at which water is being formed. B. The reactants are disappearing half as fast as the products are appearing. C. Carbon dioxide is being consumed twice as fast as oxygen is being produced. D. The rate of production of carbon dioxide is twice the rate of disappearance of methanol. Use the following to answer questions 11 and 12. Consider the reaction between O2(g) (circled) and NO(g) shown below. 11. Which of the following best represents the balanced equation for the reaction above, using the lowest possible coefficients? A. 2NO + O2 → 2NO2 B. 6NO + 3O2 → 6NO2 C. 3NO + O2 → 2NO2 + NO D. 9NO + 3O2 → 6NO2 + 3NO 12. Determine the limiting reactant shown in the picture above. A. O2 B. NO C. NO2 D. It cannot be determined. 13. A series of experiments were performed to determine the mechanism for the general reaction between A and B. In the first experiment, concentration versus time data were collected where [A]=1.1 M and [B]=7.0x10-4 M and a plot of [B] vs time resulted in a straight line plot with a negative slope. In the second experiment, concentration versus time data were collected where [A]=7.0x10-4 M and [B]=1.1 M and a plot of 1/[A] vs time resulted in a straight-line plot with a positive slope. Which of the following mechanisms is consistent with the rate law for this reaction? A. A + B ⇄ E E + A → C + D B. A + B ⇄ E E + B → C + D C. A + A → E E + B → C + D D. B + B ⇄ E E + A → C + D 14. Which of the following shows a redox reaction where hydrogen is oxidized? A. Mg(s) + 2H2O(l) → Mg(OH)2(aq) + H2(g) B. LiH(s) + H2O(l) → LiOH(aq) + H2(g) C. HF(aq) + OH-(aq) → H2O(l) + F-(aq) D. 2H2O(g) → 2H2(g) + O2(g) 15. HCI + NaOH → NaCl + H2O A student had two dilute, colorless solutions, HCI and NaOH, which were at the same temperature. The student combined the solutions, and the reaction represented above occurred. Which of the following results would be evidence that a chemical reaction took place? A. The temperature of the reaction mixture increases B. The resulting solution is colorless C. The total volume of the mixture is approximately equal to the sum of the initial volume D. The resulting solution conducts electricity 16. NH3(aq) + H2O(l) ⇄ NH2-(aq) + H3O+(aq) A strong smell of ammonia, NH3, is observed at the end of the reaction. Which of the following statements is true? A. NH3(aq) is a stronger base than H3O+(aq) is. B. NH2-(aq) is a stronger acid than H2O(l) is. C. NH2-(aq) is a stronger base than H2O(l) is. D. NH3(aq) is a stronger acid than H3O+(aq) is. Consider the following rate data for the reaction: H2O2 + 3I- + 2H+ → I3- + 2H2O [H2O2] [I-]o [H+] Initial Rate Change [H2O2] M/s 0.100 M 2.50x10-4 M 2.00x10-2 M 0.129 M/s 0.100 M 5.00x10-4 M 2.00x10-2 M 0.252 M/s 0.200 M 5.00x10-4 M 2.00x10-2 M 0.516 M/s 0.400 M 5.00x10-4 M 4.00x10-2 M 1.032 M/s A student proposed the following two mechanisms for the above reaction: **Mechanism 1** Step 1: H2O2 + I- → H2O + OI Step 2: OI- + H+ → HOI Step 3: HOI + I- + H+ → I2- + H2O Step 4: I2- + I- → I3- **Mechanism 2:** Step 1: H2O2 + I- + H+ → H2O + HOI Step 2: HOI + I- + H+ → I2- + H2O Step 3: I2- + I- → I3- 17. Which of the following is the correct description that matches the rate data? A. Mechanism 1 with the first step as the slow step B. Mechanism 1 with the second step as the slow step C. Mechanism 2 with the first step as the slow step. D. Mechanism 2 with the second step as the slow step. 18. A student is performing a titration and adds NaOH to fill the buret. The buret with NaOH is shown to the right. What should the student record as their volume? A. 5.68 mL B. 6.32 mL C. 6.3 mL D. 5.7 mL 19. Which of the following is the net ionic equation for the reaction between aqueous sodium fluoride and nitric acid? A. Na+(aq) + F-(aq) + H+(aq) + NO3-(aq) → Na+(aq) + NO3-(aq) + HF(aq) B. Na+(aq) + NO3-(aq) → NaNO3(aq) C. F-(aq) + H+(aq)→HF(aq) D. NaF(aq) + HNO3(aq) → NaNO3(aq) + HF(aq) Use the following information to answer questions 20 and 21. 3TS2(aq) + M2R3(aq) → 2MS3(s) + 3TR(s) M2R3 and TS2 are both ionic compounds. When 50.0 mL of a 1.0 M solution of TS2 and 20.0-mL of a 1.0 M solution of M2R3 are mixed, two precipitates are formed. 20. After the reaction has gone to completion, what ions remain in solution? A. T and S B. M and R C. M and S D. T and R 21. After the reaction has gone to completion, which of the following represents the number of moles of M+ ion in solution? A. 0.0067 mole B. 0.0033 mole C. 0.017 mole D. 0.010 mole 22. A student wants to find the molar mass of an unknown gas by water displacement. The student collects 40.1 mL of gas at 17.8°C and a pressure of 1.54 atm. The student finds the mass collected to be 0.12 g. The water vapor pressure at 17.8°C is 0.0191 atm. Calculate the partial pressure of the unknown gas. A. 1.52 atm B. 2.6x10-3 atm C. 46.4 atm D. 2.59 atm 23. A series of experiments were performed to determine the mechanism for the general reaction between A and B. In the first experiment, concentration versus time data were collected where [A]=1.1 M and [B]=7.0x10-4 M and a plot of [B] vs time resulted in a straight line plot with a negative slope. In the second experiment, concentration versus time data were collected where [A]=7.0x10-4 M and [B]=1.1 M and a plot of 1/[A] vs time resulted in a straight-line plot with a positive slope. Which of the following mechanisms is consistent with the rate law for this reaction? A. A + B ⇄ E E + A → C + D B. A + B ⇄ E E + B → C + D C. A + A → E E + B → C + D D. B + B ⇄ E E + A → C + D 24. Which of the following shows a redox reaction where hydrogen is oxidized? A. Mg(s) + 2H2O(l) → Mg(OH)2(aq) + H2(g) B. LiH(s) + H2O(l) → LiOH(aq) + H2(g) C. HF(aq) + OH-(aq) → H2O(l) + F-(aq) D. 2H2O(g) → 2H2(g) + O2(g) 25. If 200 mL of 0.6 M K2SO4(aq) is added to 300 mL of distilled water, what is the concentration of K+(aq) in the resulting solution? (assume volumes are additive) A. 0.24 M B. 0.80 M C. 0.48 M D. 0.12 M 26. Which of the following has the highest boiling point? A. KNO3 B. NH3 C. H2O D. HCI 27. The total pressure in the container to the right is 7.5 atm. Calculate the partial pressure of argon in the container. A. 0.94 atm B. 4.69 atm C. 1.88 atm D. 6.00 atm 28. On a cold day near the ocean, it was found that 8 g of an unknown gas occupies a volume that is a little less than 6 L. Based on this information, what is the most likely identity of the unknown gas? A. CO2 B. O2 C. Ne D. CH4 29. Which molecule is likely to have a dipole-dipole intermolecular force? 30. Which compound would be expected to be the most soluble in octane, C8H18? A. CH3OCH3 B. CHBr3 C. CO2 D. CH3NH3 31. Two identical railroad tanker cars are evacuated and then each is filled with 1.20x10^3 moles of a gas at 27°C. Tank car 1 is filled with sulfur dioxide while Tank car 2 is filled with carbon monoxide. Initially, the pressures in the tanks are equal. During a train derailment, identical pin-sized holes are made in each tank car; the decrease in pressure of each tank car is monitored. One of the tank cars has a much more rapid decrease in pressure than the other. Which statement best explains this? A. The pressure in Tank Car 1 decreases more rapidly because the heavier molecules of SO2 have a greater velocity than that of CO molecules. B. The pressure in Tank Car 1 decreases more rapidly because there are more molecules of SO2 than molecules of CO. C. The pressure in Tank Car 2 decreases more rapidly because CO molecules are lighter and have a higher velocity than SO2 molecules. D. The pressure in Tank Car 2 decreases more rapidly because there are more molecules of CO than molecules of SO2. 32. Which of the following is the best explanation of how ions in KCI interact with a water molecule in the process of dissolution? A. The K+ ions are attracted to the hydrogen end of the water molecule, and the Cl ions are attracted to the oxygen end. B. The K+ ions are attracted to the oxygen end of the water molecule, and the Cl ions are attracted to the hydrogen end. C. Both the K and Cl ions are attracted to the oxygen end of the water molecule. D. Both the K+ and Cl ions are attracted to the hydrogen end of the water molecule. 33. Which of the following gases will condense first? A. O2(g) B. H2(g) C. HCI(g) D. HF(g) 34. The attractions between the C3H8 molecules that hold the molecules together in the solid state are best identified as A. polar covalent bonds B. nonpolar covalent bonds C. intermolecular attractions resulting from permanent dipoles D. intermolecular attractions resulting from temporary dipoles 35. In the diagram to the right, which of the labeled arrows identifies hydrogen bonding in water? A. A B. B C. C D. D 36. Which of the following is most likely to be a solid at room temperature? A. N2 B. CaS C. CH4 D. HF 37. Which of the following is the molecular formula of the unknown compound in the reaction below? ? + 5O2(g) → 4CO2(g) + 4H2O(l) A. C4H8O B. C4H8O2 C. C4H8O4 D. C4H8O12 38. The experimental apparatus represented to the right is used to demonstrate the rate at which gases diffuse. When the cotton balls coated in different gases are placed in the ends of a tube at the same time, the gases diffuse from each and meet somewhere in between, where they react. Which of the following combinations will produce a reaction closest to the center of the tube? A. HCI and NH3 B. NH3 and CH4 C. HBr and C2H6 D. HBr and NH3 39. A student is asked to determine the identity of three different aqueous solutions of equal molarity. The solutions are Ca(C2H3O2)2, C6H12O6, and K3PO4 in no particular order. The student uses a conductivity meter and tests the conductivity of equal volumes of each solution. The results are shown to the right: Which beaker contains Ca(C2H3O2)2? A. Beaker 1 B. Beaker 2 C. Beaker 3 D. Cannot be determined 40. The Maxwell-Boltzmann distributions of molecular speeds in samples of two different gases at the same temperature are shown above left. Which gas has the greater molar mass? A. Gas A B. Gas B C. Both gases have the same molar mass. D. It cannot be determined unless the pressure of each sample is known. 41. Which of the following describes the changes in the forces of attraction that occur as H2O changes phase from a liquid to a vapor? A. H-O bonds break as H-H and O-O bonds form. B. Ionic bonds between H+ and OH- ions are broken C. Covalent bonds between H2O molecule are broken D. Hydrogen bonds between H2O molecules are broken 42. As the number of bonds between two carbon atoms increases, which of the following decreases? A. Bond length B. Bond strength C. Both bond length and bond strength D. Neither bond length nor bond strength 43. When bonding with a chlorine atom, which of the following atoms will yield the least polar bond? A. I B. P C. S D. Ca 44. In the molecule shown below, what are the approximate bond angles for a, b, and c, respectively? a b c H :O: H C – C – C = C – H H A. a = 90°; b = 90°; c = 90° B. a = 90°; b = 120°; c = 180° C. a = 109.5°; b = 90°; c = 180° D. a = 109.5°; b = 120°; c = 180° 45. Which of the following choices consists of a pair of isotopes? A. 14C and 14N B. 23Na and 23Na+ C. 1H and 1H+ D. 35Cl and 35Cl- ## Unit 1-2 Test MCQ 1. Consider the following electron configurations for neutral atoms: Atom A= 1s22s22p63s2 Atom B = 1s22s22p63s23p1 Atom C = 1s22s22p63s23p2 Which atom would be expected to have the largest third ionization energy? A. Atom A B. Atom B C. Atom C D. All of these atoms would be expected to have the same third ionization energy. 2. The four spheres to the right represent Na+, Mg2+, O2-, and F-, not necessarily in that order. Which sphere most likely represents the F- ion? A. Sphere A B. Sphere B C. Sphere C D. Sphere D 3. The pictures to the right represent alkali halide salts with the same ion charges. Which salt has the lowest lattice energy? A. Picture A B. Picture B C. Picture C D. Picture D 4. The complete photoelectron spectrum for an element is shown to the right. Which of the following observations would provide evidence that the spectrum is consistent with the atomic model of the element? A. A neutral atom of the element contains exactly eight electrons. B. The element does not react with other elements to form compounds. C. In its compounds, the element tends to form ions with a charge of +1 D. In its compounds, the elements tends to form ions with a charge of +3 5. Carmustine is a chemotherapeutic agent with a formula of C5H9Cl2N3O2 (molar mass = 214.05 g/mol). What mass (in grams) of Carmustine contains 5.6x10^19 hydrogen atoms? A. 1.99x10-2 B. 0.179 C. 2.2x10-3 D. 9.30x10-5 6. In an experiment, 25.0-g samples of four different elements from the fourth period of the periodic table were measured out. The four elements are calcium, chromium, cobalt, and copper. Which sample contained the greatest number of atoms? A. Ca B. Cr C. Co D. Cu 7. The table shows the first ionization energies of element X in kJ/mol. First IE 738 Second IE 7750 Third IE 9125 What is the most likely formula of the compound between elements X and Y, where Y has 6 valence electrons? A. X2Y B. XY2 C. XY3 D. XY 8. When observing PES of individual elements, which of the following pairs of elements would have their lowest energy peaks at different heights? A. Li and B B. Mg and C C. Na and Cl D. H and Al 9. What is the electron configuration for V2+? A. 1s22s22p63s23p63d3 B. 1s22s22p63s23p63d5 C. 1s22s22p63s23p63d34s2 D. 1s22s22p63s23p63d54s2 10. Of HCO3- and CO32-, which one has the shortest C-O bond length? A. HCO3- B. CO32- C. They have the same bond length D. This cannot be determined 11. The PES diagram to the right shows only the 1s electrons of chlorine and argon. Identify which peak belongs to argon along with the correct justification. A. The argon peak is on the left. As a noble gas, its core electrons are more stable and harder to remove. B. The argon peak is on the left. Argon has one more proton than does chlorine, causing its electrons to be held more tightly. C. The chlorine peak is on the left. Chlorine is a halogen and gains one electron easily to obtain a noble gas electron configuration. D. The chlorine peak is on the left. Chlorine has one less proton than does argon, making it easier to remove an electron. 12. Which molecule is likely to have a measurable dipole moment? 13. The lattice energies of four compounds of iron (FeCl2, FeCl3, FeO, Fe2O3) are shown below. Which choice correctly matches the lattice energies with the compounds? Lattice Energy (kJ/mol) 2605 3830 5400 14541 A. FeO Fe2O3 FeCl2 FeCl3 B. FeCl2 FeO FeCl3 Fe2O3 C. Fe2O3 FeCl3 FeCl2 FeO D. FeCl2 FeCl3 FeO Fe2O3 14. Which of the following has sp3 hybridization and has a bond angle closest to 105°? 15. Which substance can be described as cations bonded together by mobile electrons? A. KCI(s) B. HCI(l) C. Ag(s) D. Kr(l) 16. Carbon atoms and iron atoms combine to make the alloy steel. Based on this information, which of the following diagrams best represents an alloy containing only carbon and iron atoms? 17. Consider the following electron configurations for neutral atoms: Atom A= 1s22s22p63s2 Atom B = 1s22s22p63s23p1 Atom C = 1s22s22p63s23p2 Which atom would be expected to have the largest fourth ionization energy? A. Atom A B. Atom B C. Atom C D. All of these atoms would be expected to have the same fourth ionization energy. 18. The four spheres to the right represent Na+, Mg2+, O2-, and F-, not necessarily in that order. Which sphere most likely represents the F- ion? A. Sphere A B. Sphere B C. Sphere C D. Sphere D 19. The pictures to the right represent alkali halide salts with the same ion charges. Which salt has the lowest lattice energy? A. Picture A B. Picture B C. Picture C D. Picture D 20. The complete photoelectron spectrum for an element is shown to the right. Which of the following observations would provide evidence that the spectrum is consistent with the atomic model of the element? A. A neutral atom of the element contains exactly eight electrons. B. The element does not react with other elements to form compounds. C. In its compounds, the element tends to form ions with a charge of +1 D. In its compounds, the elements tends to form ions with a charge of +3 21. Carmustine is a chemotherapeutic agent with a formula of C5H9Cl2N3O2 (molar mass = 214.05 g/mol). What mass (in grams) of Carmustine contains 5.6x10^19 hydrogen atoms? A. 1.99x10-2 B. 0.179 C. 2.2x10-3 D. 9.30x10-5 22. In an experiment, 25.0-g samples of four different elements from the fourth period of the periodic table were measured out. The four elements are calcium, chromium, cobalt, and copper. Which sample contained the greatest number of atoms? A. Ca B. Cr C. Co D. Cu 23. The table shows the first ionization energies of element X in kJ/mol. First IE 738 Second IE 7750 Third IE 9125 What is the most likely formula of the compound between elements X and Y, where Y has 6 valence electrons? A. X2Y B. XY2 C. XY3 D. XY 24. When observing PES of individual elements, which of the following pairs of elements would have their lowest energy peaks at different heights? A. Li and B B. Mg and C C. Na and Cl D. H and Al 25. What is the electron configuration for V2+? A. 1s22s22p63s23p63d3 B. 1s22s22p63s23p63d5 C. 1s22s22p63s23p63d34s2 D. 1s22s22p63s23p63d54s2 26. Of HCO3- and CO32-, which one has the shortest C-O bond length? A. HCO3- B. CO32- C. They have the same bond length D. This cannot be determined 27. The PES diagram to the right shows only the 1s electrons of chlorine and argon. Identify which peak belongs to argon along with the correct justification. A. The argon peak is on the left. As a noble gas, its core electrons are more stable and harder to remove. B. The argon peak is on the left. Argon has one more proton than does chlorine, causing its electrons to be held more tightly. C. The chlorine peak is on the left. Chlorine is a halogen and gains one electron easily to obtain a noble gas electron configuration. D. The chlorine peak is on the left. Chlorine has one less proton than does argon, making it easier to remove an electron. 28. Which molecule is likely to have a measurable dipole moment? 29. The lattice energies of four compounds of iron (FeCl2, FeCl3, FeO, Fe2O3) are shown below. Which choice correctly matches the lattice energies with the compounds? Lattice Energy (kJ/mol) 2605 3830 5400 14541 A. FeO Fe2O3 FeCl2 FeCl3 B. FeCl2 FeO FeCl3 Fe2O3 C. Fe2O3 FeCl3 FeCl2 FeO D. FeCl2 FeCl3 FeO Fe2O3 30. Which of the following has sp3 hybridization and has a bond angle closest to 105°? 31. Which substance can be described as cations bonded together by mobile electrons? A. KCI(s) B. HCI(l) C. Ag(s) D. Kr(l) 32. Carbon atoms and iron atoms combine to make the alloy steel. Based on this information, which of the following diagrams best represents an alloy containing only carbon and iron atoms? 33. Which compound would be expected to be the most soluble in water? A. CH3OCH3 B. CHBr3 C. C6H14 D. CH3NH3 34. Two identical railroad tanker cars are evacuated and then each is filled with 1.20x10^3 moles of a gas at 27°C. Tank car 1 is filled with sulfur dioxide while Tank car 2 is filled with carbon monoxide. Initially, the pressures in the tanks are equal. During a train derailment, identical pin-sized holes are made in each tank car; the decrease in pressure of each tank car is monitored. One of the tank cars has a much more rapid decrease in pressure than the other. Which statement best explains this? A. The pressure in Tank Car 1 decreases more rapidly because the heavier molecules of SO2 have a greater velocity than that of CO molecules. B. The pressure in Tank Car 1 decreases more rapidly because there are more molecules of SO2 than molecules of CO. C. The pressure in Tank Car 2 decreases more rapidly because CO molecules are lighter and have a higher velocity than SO2 molecules. D. The pressure in Tank Car 2 decreases more rapidly because there are more molecules of CO than molecules of SO2. 35. Which of the following is the best explanation of how ions in KCI interact with a water molecule in the process of dissolution? A. The K+ ions are attracted to the hydrogen end of the water molecule, and the Cl ions are attracted to the oxygen end. B. The K+ ions are attracted to the oxygen end of the water molecule, and the Cl ions are attracted to the hydrogen end. C. Both the K and Cl ions are attracted to the oxygen end of the water molecule. D. Both the K+ and Cl ions are attracted to the hydrogen end of the water molecule. 36. Which of the following gases will condense first? A. O2(g) B. H2(g) C. HCI(g) D. HF(g) 37. The attractions between the C3H8 molecules that hold the molecules together in the solid state are best identified as A. polar covalent bonds B. nonpolar covalent bonds C. intermolecular attractions resulting from permanent dipoles D. intermolecular attractions resulting from temporary dipoles 38. In the diagram to the right, which of the labeled arrows identifies hydrogen bonding in water? A. A B. B C. C D. D 39. Which of the following is most likely to be a solid at room temperature? A. N2 B. CaS C. CH4 D. HF 40. Which of the following is the molecular formula of the unknown compound in the reaction below? ? + 5O2(g) → 4CO2(g) + 4H2O(l) A. C4H8O B. C4H8O2 C. C4H8O4 D. C4H8O12