PRACTICE CHEMISTRY EOC TEST 1. Which substance is a conductor of electricity? (A) NaCl(s) (B) NaCl(l) (C) C6H12O6(s) (D) C6H12O6(l) REASON: Conductors of electricity (electrolytes) must be ionic (metal & nonmetal) and either liquid or dissolved in water. 2. Which formula is correctly paired with its name? (A) MgCl2 magnesium chlorine (B) K2O potassium dioxide (C) CoCl2 copper (II) chloride (D) FeO iron (II) oxide REASON: correct name for (A) would be magnesium chloride, (B) = potassium oxide, (C) = cobalt (II) chloride 3. What is the molarity of a KF(aq) solution containing 116 grams of KF in 1.00 liter of solution? (A) 1.00 M (B) 2.00 M (C) 3.00 M (D) 4.00 M REASON: M = moles solute 116 g KF x 1 mole KF = 2.00 moles KF liters sol n 58 g KF 2.00 moles KF = 2.00 M 1.00 Liter 4. Which compound has the LEAST ionic character? (A) KCl (B) AlCl3 (C) CCl4 (D) CaCl2 REASON: Ionic = metal & nonmetal. Therefore, least ionic would have 2 nonmetals. 5. Which is the electron configuration of an atom of a Period 3 element? (A) 1s 2 2s 1 (B) 1s 2 2s 2 2p 3 (C) 1s 2 2p 1 (D) 1s 2 2s 2 2p 6 3s 1 REASON: Either add up exponents to get atomic number of element and see which is in Period 3 OR look for HOEL (biggest non-exponent number). 6. Which of the following elements has the largest atomic radius? (A) strontium (B) tin (C) rubidium (D) iodine REASON: largest AR is at the bottom left of the Periodic Table 7. At STP, 32.0 liters of O2 contain the same number of molecules as (A) 22.4 liters of Ar (B) 32.0 liters of H2 (C) 28.0 liters of N2 (D) 44.8 liters of He REASON: at the same temperature & pressure, equal volumes of gas have equal # of moles and therefore, equal # of molecules 8. When a metal reacts with a nonmetal, the metal will (A) lose electrons and form a positive ion (B) lose protons and form a positive ion (C) gain electrons and form a negative ion (D) gain protons and form a negative ion REASON: metals are on the left side of the PT & usually have 3 or fewer valence e-, so metals want to lose electrons. When an atom loses an electron, it becomes a positive ion. 9. According to the Arrhenius theory, a substance that is classified as an acid will always yield (A) H +1 (aq) (B) OH -1 (aq) (C) NH4 +1 (aq) (D) CO3-2 (aq) REASON: definition of Arrhenius acid 10. What is the net ionic equation for a neutralization reaction? (A) H +1 + H2O H3O +1 (B) H +1 + NH3 NH4 +1 (C) 2 H +1 + 2 O -2 2 OH -1 (D) H +1 + OH -1 H2O REASON: Neutralization reaction is an acid (H +1 ions) reacting with a base (OH -1 ions) 11. The oxidation number of nitrogen in N2O is (A) +1 (B) +2 (C) 1 (D) 2 REASON: let x = oxidation number of N (2. x) + (1. -2) = 0 2x 2 = 0 N O x = +1
12. How many milliliters of 4.00 M NaOH are required to exactly neutralize 50.0 milliliters of a 2.00 M solution of HNO3? (A) 25.0 ml (B) 100. ml (C) 50.0 ml (D) 200. ml REASON: namava = nbmbvb 1. 2.00 M. 50.0 ml = 1. 4.00 M. V 100 = 4 V V = 25.0 ml 13. Why is salt (NaCl) put on icy roads and sidewalks in the winter? (A) It is ionic and lowers the freezing point of water. (B) It is ionic and raises the freezing point of water. (C) It is covalent and lowers the freezing point of water. (D) It is covalent and raises the freezing point of water. REASON: Ionic = metal & nonmetal = larger value = larger difference in BP or FP. BP of solutions are always higher than that of the solvent. FP of solutions are always lower than that of the solvent. 14. Which gas diffuses most rapidly at STP? (A) Ar (B) Kr (C) O2 (D) N2 REASON: lowest molar mass = effuses fastest (A) 39.95 (B) 83.80 (C) 32.00 (D) 28.00 15. Which formulas represent a conjugate acid-base pair? (A) CH3COOH and CH3COO -1 (B) H3O +1 and OH -1 (C) H2SO4 and SO4-2 (D) H3PO4 and PO4-3 REASON: Conjugate acid-base pairs can only be different from one another by one H +1. 16. Which group below contains elements with the greatest variation in chemical properties? (A) Li, Be, B (B) B, Al, Ga (C) Li, Na, K (D) Be, Mg, Ca REASON: Elements in the same group have similar properties. Elements in (A) are NOT in same group. 17. What is the total number of electrons in a Mg +2 ion? (A) 2 (B) 10 (C) 12 (D) 14 REASON: Mg normally has 12 electrons total. +2 oxidation number means that it lost 2 electrons for a total of 10. 18. Which is a molecular substance? (A) CO2 (B) KCl (C) KClO3 (D) CaO REASON: Molecular substance = covalent bonds = all nonmetals 19. Which reaction system s entropy DECREASES as reactants form products? (A) C(s) + O2(g) CO2(g) (B) S(s) + O2(g) SO2(g) (C) I2(s) + Cl2(g) 2 ICl(g) (D) 2 Mg(s) + O2(g) 2 MgO(s) REASON: Entropy increases from solid liquid gas 20. Which substance CANNOT be decomposed by a chemical change? (A) ammonia (B) methane (C) water (D) carbon REASON: Compounds can be decomposed by a chemical change elements cannot. ammonia = NH3, methane = CH4, water = H2O 21. Given the equilibrium system at 25 o C: NH4Cl(s) NH4 +1 (aq) + Cl -1 (aq) (ΔH = + 3.5 kcal/mole) Which change will shift the equilibrium to the right? (A) decreasing the temperature to 15 o C (B) increasing the temperature to 35 o C (C) dissolving NaCl crystals in the equilibrium mixture (D) dissolving NH4NO3 crystals in the equilibrium mixture REASON: ΔH value is positive, so reaction is endothermic (energy/heat is on left side of arrow). To shift right, reactants have to be increased, so if temp increases, then heat increases and heat is a reactant.
22. Which ion has the electron configuration of a noble gas? (A) Cu +2 (B) Ca +2 (C) Hg +2 (D) Fe +2 REASON: +2 oxidation number means lost 2 e-. Cu normally has 29 electrons. Cu +2 has 27 e-. Ca +2 has 18, Hg +2 has 78, Fe +2 has 24. The only atomic number equal to that of a noble gas is Ca +2 (18). 23. Which phase change results in a release of energy? (A) Br2(l) Br2(s) (B) H2O(s) H2O(l) (C) I2(s) I2(g) (D) NH3(l) NH3(g) REASON: Energy is released when going from gas liquid solid Energy is absorbed when going from solid liquid gas 24. As HCl (aq) is added to a basic solution, the ph of the solution will (A) decrease (B) increase (C) remain the same REASON: By definition, bases have a ph over 7, acids have a ph lower than 7. HCl is an acid, so it would decrease the ph. 25. A property of most nonmetals in the solid state is that they are (A) good conductors of heat (B) good conductors of electricity (C) brittle (D) malleable REASON: Question refers to nonmetals. Metals are good conductors of heat and electricity and are malleable. Nonmetals are not. 26. What is the mass in grams of 3.0 x 10 23 molecules of CO2? (A) 22 g (B) 44 g (C) 66 g (D) 88 g REASON: 3.0 x 10 23 molecules CO2 x 44 g CO2 = 22 g 6.022 x 10 23 mcs CO2 27. An atom of an element has the electron configuration 1s 2 2s 2 2p 2. What is the total number of valence electrons in this atom? (A) 6 (B) 2 (C) 5 (D) 4 REASON: Valence electrons are electrons in the highest occupied energy level (HOEL). Either: add up exponents to get atomic number === 6, which is carbon, which is in group 14, so it has 4 valence electrons Or: Add up exponents in HOEL (largest coefficient/non-exponent number) 1s 2 2s 2 2p 2 2 + 2 = 4 28. Given the reaction: 2 PbO 2 Pb + O2 What is the total volume of O2, measured at STP, produced when 1.00 mole of PbO decomposes? (A) 5.60 L (B) 22.4 L (C) 11.2 L (D) 44.8 L REASON: Stoichiometry problem! Given moles, asked for liters, so use steps 2 & 3. 1.00 mole PbO = x moles O2 2 x = 1 2 1 x = 0.5 moles O2 0.5 moles x 22.4 L = 11.2 L 1 mole 29. Given the nuclear equation: 9 4Be + X 6 3Li + 4 2He What is the identity of particle X in this equation? (A) 1 1H (B) 1 0n (C) 0-1e (D) 2 1H REASON: Top #s and bottom #s must be equal on both sides of the eqn. top: 9 + x = 6 + 4 x = 1 (top number) bottom: 4 + x = 3 + 2 x = 1 (bottom number) 30. Which atoms contain the same number of neutrons? (A) 1 1H and 3 2He (B) 3 1H and 3 2He (C) 2 1H and 4 2He (D) 3 1H and 4 2He REASON: # of neutrons = mass number minus atomic number (top # minus bottom #) (A) 0 and 1 (B) 2 and 1 (C) 1 and 2 (D) 2 and 2
31. Which atom contains exactly 15 protons? (A) phosphorus-32 (B) oxygen-15 (C) sulfur-32 (D) nitrogen-15 REASON: Number of protons is determined by the atomic number of the element. If an element has 15 protons, it MUST be phosphorus, regardless of the mass #. 32. Which is a correctly balanced equation for a reaction between hydrogen gas and oxygen gas? (A) H2(g) + O2(g) H2O(l) + heat (B) H2(g) + O2(g) 2 H2O(l) + heat (C) 2 H2(g) + 2 O2(g) H2O(l) + heat (D) 2 H2(g) + O2(g) 2 H2O(l) + heat REASON: (A), (B), and (C) are not balanced correctly 33. The atom of which element has an ionic radius smaller than its atomic radius? (A) N (B) S (C) Br (D) Rb REASON: ionic radius smaller than atomic radius means that the element gets smaller when it loses or gains electrons. Elements that lose electrons get smaller. Elements that gain electrons get larger. 34. Atoms of elements in a group on the Periodic Table have similar chemical properties. This similarity is most closely related to the atoms' (A) number of principal energy levels (B) number of valence electrons (C) atomic numbers (D) atomic masses REASON: Elements in the same group have similar properties. Elements in the same group have the same electron configuration in their outermost energy level. 35. Which element in Period 2 of the Periodic Table is the most reactive nonmetal? (A) fluorine (B) oxygen (C) beryllium (D) lithium REASON: Beryllium & lithium are metals, so they are not correct answers. The most reactive nonmetals are members of group 17. 36. Given the reaction: Ca(s) + 2 H2O(l) Ca(OH)2(aq) + H2(g) When 40.1 grams of Ca(s) react completely with the water, what is the total volume, at STP, of H2(g) produced? (A) 1.00 L (B) 2.00 L (C) 22.4 L (D) 44.8 L REASON: Stoichiometry problem! Use steps 1,2, and 3. 40.1 g x 1 mole = 1 mole Ca 40.1 g 1 mole Ca = x moles H2 x = 1 mole H2 1 1 1 mole x 22.4 L = 22.4 L 1 mole 37. As atoms of elements in Group 16 are considered in order from top to bottom, the electronegativity of each successive element (A) decreases (B) increases (C) remains the same REASON: Highest electronegativity is at the top right of the Periodic Table (not including Noble Gases). 38. Given the change of phase CO2(g) CO2(s) As CO2(g) changes to CO2(s), the entropy of the system (A) decreases (B) increases (C) remains the same REASON: Entropy increases from solid liquid gas 39. Electron X can change to a higher or a lower energy level. Which statement is true of electron X? (A) Electron X emits energy when it changes to a higher energy level. (B) Electron X absorbs energy when it changes to a higher energy level. (C) Electron X absorbs energy when it changes to a lower energy level. (D) Electron X neither emits nor absorbs energy when it changes energy level. REASON: Electrons absorb energy when going to a higher energy level, and lose/emit energy when falling to a lower energy level.
40. The oxide of metal X has the formula X2O. Which group in the Periodic Table contains metal X? (A) Group 1 (B) Group 13 (C) Group 17 (D) Group 2 REASON: (2. x) + (1. -2) = 0 2x -2 = 0 X O x = +1 Group 1 elements have an oxidation # of +1. 41. A student determined the heat of fusion of water to be 88 calories per gram. If the accepted value is 80. calories per gram, what is the student s percent error? (A) 8.0% (B) 10.% (C) 11% (D) 90.% REASON: % error = accepted value experimental value x 100 accepted value 80 88 = 10. % 80 42. What is the empirical formula of a compound that contains 85% Ag and 15% F by mass? (A) AgF (B) Ag2F (C) AgF2 (D) Ag2F2 REASON: 85 g Ag x 1 mole Ag = 0.787 moles Ag 15 g F x 1 mole F = 0.789 moles F 108 g Ag 19 g F then, divide by smallest # of moles. Those answers are the subscripts in the formula. Base your answer to questions 43 and 44 on the table below, which represents the production of 50 milliliters of CO2 in the reaction of HCl and NaHCO3. Five trials were performed under different conditions as shown. (The same mass of NaHCO3 was used in each trial.) Trial Particle Size of NaHCO3 Concentration of HCl Temperature of HCl ( o C) A Small 1 M 20 B Large 1 M 20 C Large 1 M 40 D Small 2 M 40 E Large 2 M 40 43. Which two trials could be used to measure the effect of surface area? (A) trials A and B (B) trials A and D (C) trials A and C (D) trials B and D REASON: surface area is tested with particle size. All other factors (concentration & temp) should be the same. 44. Which trial would produce the fastest reaction? (A) trial A (B) trial E (C) trial C (D) trial D REASON: small particles (most surface area), highest concentration, highest temp. = fastest reaction 45. The graph below represents the uniform cooling of a sample of a substance, starting with the substance as a gas above its boiling point. Which segment of the curve represents a time when both the liquid and the solid phases are present? (A) EF (B) CD (C) BC (D) DE REASON: AB is in the gas phase. BC is condensing (gas to liquid). CD is in the liquid phase. DE is freezing (liquid to solid). 46. Which element in Group 15 would most likely have luster and good electrical conductivity? (A) N (B) P (C) Bi (D) As
REASON: luster & good conductivity are properties of metals. Most metallic character is at the bottom of a group 47. The potential energy diagram below shows the reaction X + Y Z When a catalyst is added to the reaction, it will change the value of (A) 1 and 2 (B) 2 and 3 (C) 1 and 3 (D) 3 and 4 REASON: catalyst lowers the activation energy, so numbers that reach dashed line at the top will be affected 48. As the temperature of a given sample of a gas is increased at constant pressure, the volume of the gas will (A) decrease (B) increase (C) remain the same REASON: temperature and volume are directly proportional (Charles Law), so when temp increases, volume increases also. 49. Given the electron dot formula: The attraction for the bonding electrons would be the greatest when X represents an atom of (A) S (B) O (C) Se (D) Te REASON: attraction for bonding electrons = electronegativity. Highest electronegativity is at the top right of the Periodic Table (not including Noble Gases). 50. Which is a property of a reaction that has reached equilibrium? (A) The amount of products is greater than the amount of reactants. (B) The amount of products is equal to the amount of reactants. (C) The rate of the forward reaction is greater than the rate of the reverse reaction. (D) The rate of the forward reaction is equal to the rate of the reverse reaction. REASON: Definition of equilibrium. 51. Which procedure will increase the solubility of KCl in water? (A) stirring the solute and solvent mixture (B) increasing the surface area of the solute (C) raising the temperature of the solvent (D) increasing the pressure on the surface of the solvent REASON: Remember that the question asks about increasing the solubility (amount that dissolves) of KCl, not the rate (how fast) the KCl dissolves. Temperature is the only factor that will affect the amount of solid solute that can be dissolved in a given amount of water. 52. Which reaction best illustrates amphoterism? (A) H2O + HCl H3O +1 + Cl -1 (B) NH3 + H2O NH4 +1 + OH -1 (C) H2O + H2SO4 H3O +1 + HSO4-1 (D) H2O + H2O H3O +1 + OH -1 REASON: Amphoterism = acting like an acid and a base. In (D), H2O acts like an acid when it becomes OH -1 and acts like a base when it becomes H3O +1.
53. The bond between hydrogen and oxygen in a water molecule is classified as (A) ionic and nonpolar (B) ionic and polar (C) covalent and nonpolar (D) covalent and polar REASON: Hydrogen and oxygen are both nonmetals (covalent). Because they are two different nonmetals, that means that the bond is polar. 54. What is the oxidation number of carbon in NaHCO3? (A) +6 (B) 4 (C) +2 (D) +4 REASON: Let x = oxidation # of C in compound (1. +1) + (1. +1) + (1. x) + (3. -2) = 0 1 + 1 + x 6 = 0 Na H C O x = +4 55. The conjugate acid of the HS -1 ion is (A) H +1 (B) H2O (C) S -2 (D) H2S REASON: finding conjugate acid means that the substance acted like a base. A base gains an H +1. HS -1 + H +1 = H2S 56. In an aqueous solution of an ionic salt, the oxygen atom of the water molecule is attracted to the (A) negative ion of the salt, due to oxygen s partial positive charge (B) negative ion of the salt, due to oxygen s partial negative charge (C) positive ion of the salt, due to oxygen s partial positive charge (D) positive ion of the salt, due to oxygen s partial negative charge REASON: oxygen atom is more electronegative than hydrogen atom thus giving it a partial negative charge. Negative charge is attracted to positive charge. 57. Given the reaction at equilibrium: N2(g) + O2(g) 2 NO(g) As the concentration of N2(g) increases, the concentration of O2(g) will (A) decrease (B) increase (C) remain the same REASON: According to LeChatelier s Principle, the forward reaction will be favored if the concentration of a reactant (N2) increases. This uses up (decreases) the concentration of O2. 58. As the elements in Group 2 are considered in order of increasing atomic number, the atomic radius of each successive element increases. This increase is primarily due to an increase in the number of (A) occupied energy levels (B) electrons in the outermost energy level (C) neutrons in the nucleus (D) unpaired electrons REASON: more and more energy levels are occupied with each successive element as you move down through a group 59. What is the correct equilibrium expression for the reaction 2 A(g) + 3 B(g) C(g) + 3 D(g)? (A) K = [2 A] + [3 B] (B) K = [A] 2 [B] 3 [C] + [3 D] [C] [D] 3 (C) K = [C] + [3 D] (D) K = [C] [D] 3 [2 A] + [3 B] [A] 2 [B] 3 REASON: In a Keq expression, products are written in numerator, and reactants are written in the denominator. Substances are written in brackets and raised to a power equal to their coefficient in the balanced equation. 60. Which reactant is most likely to have d electrons involved in a chemical reaction? (A) a halogen (B) a noble gas (C) a transition metal (D) an alkali metal REASON: Unfilled d sublevels occur in groups 3 12 the transition metals. 61. A real gas would behave most like an ideal gas under conditions of (A) low pressure and low temperature (B) low pressure and high temperature (C) high pressure and low temperature (D) high pressure and high temperature
REASON: the particles of ideal gases do not exert forces on each other. If there is low pressure, the molecules are not forced to be near each other (so less force exerted on them). If there is high temperature, the molecules are moving very fast, so the particles do not have time to exert forces on one another. 62. A student observed the following reaction: AlCl3(aq) + 3 NaOH(aq) Al(OH)3(s) + 3 NaCl(aq) After the products were filtered, which substance remained on the filter paper? (A) NaCl (B) AlCl3 (C) NaOH (D) Al(OH)3 REASON: Substance that would remain on the filter paper is the solid. (s) = solid 63. In which reaction is water acting only as a Bronsted-Lowry base? (A) H2SO4(aq) + H2O(l) HSO4-1 (aq) + H3O +1 (aq) (B) NH3(g) + H2O(l) NH4 +1 (aq) + OH -1 (aq) (C) CH3COO -1 (aq) + H2O(l) CH3COOH(aq) + OH -1 (aq) (D) H2O(l) + H2O(l) H3O +1 (aq) + OH -1 (aq) REASON: Bronsted-Lowry bases gain an H +1. 64. Which type of reaction occurs when 50 milliliter quantities of Ba(OH)2(aq) and H2SO4(aq) are combined? (A) reduction (B) oxidation (C) ionization (D) neutralization REASON: Ba(OH)2 is a base and H2SO4 is an acid 65. The table below shows the data collected by a student as heat was applied at a constant rate to a solid below its freezing point. Time (min) Temperature ( o C) Time (min) Temperature ( o C) 0 20 18 44 2 24 20 47 4 28 22 51 6 32 24 54 8 32 26 54 10 32 28 54 12 35 30 54 14 38 32 58 16 41 34 62 What is the boiling point of this substance? (A) 32 o C (B) 62 o C (C) 54 o C (D) 100 o C REASON: starts as a solid below its freezing point. In data table, time 0 through 4, temperature increases, then temperature levels off (for time 6 10) at 32 o C which would be the melting point. It levels off again at 54 o C. That would be the boiling point. 66. Which of the following species CANNOT act as both a Bronsted-Lowry acid and base? (A) HSO3-1 (B) HS -1 (C) H2O (D) CN -1 REASON: B-L Acids need to be able to donate an H+1, so (D) cannot act as an acid because it doesn t have an H to donate. 67. Which of the following is the correct ground state electron configuration of gallium (Ga)? (A) [Ar] 4s 2 4d 10 5p 1 (B) [Kr] 4s 2 3d 10 4p 1 (C) [Kr] 5s 2 5d 10 5p 1 (D) [Ar] 4s 2 3d 10 4p 1 REASON: Ar is closest noble gas to Ga with a lower atomic number. Ga is in Period 4, so after [Ar] would be 4s. Continue with diagonal rule. 68. What is the total number of valence electrons for a molecule of PH3? (A) 8 (B) 10 (C) 18 (D) 34 REASON: P is in group 15, so it has 5 valence electrons. H is in group 1, so each has 1 valence electron. 3 H s = 3 valence electrons + 5 valence electrons from P = total of 8 valence electrons
69. Which of the following molecules is polar? (A) HCl (B) CO2 (C) BCl3 (D) CH4 REASON: Polar molecules have unshared electron pairs around the central atom and/or different surrounding atoms. If there are only two atoms in a molecule, then bond between them also equals molecular polarity. (A) has only two atoms. H and Cl are different nonmetals, so bond and molecule are therefore polar. 70. The most reactive metals on the Periodic Table have (A) large radii and high electronegativities (B) large radii and low electronegativities (C) small radii and high electronegativities (D) small radii and low electronegativities REASON: Reactive metals are on the left side of the table at the bottom. At the bottom, radii are large and electronegativities are low. 71. What type of forces must be overcome when liquid ammonia vaporizes? 1. covalent bonds 2. London dispersion forces 3. hydrogen bonds (A) 1 only (B) 2 only (C) 2 and 3 only (D) 1, 2, and 3 REASON: when ammonia vaporizes, it is still ammonia just in gaseous form. The covalent bonds are not broken during vaporization. 72. Fe3O4(s) + 4 H2(g) 3 Fe(s) + 4 H2O(g) (ΔH > 0) For this reaction at equilibrium, which change(s) will increase the quantity of Fe(s)? 1. increasing temperature 2. decreasing pressure 3. adding Fe3O4(s) (A) 1 only (B) 1 and 2 only (C) 2 and 3 only (D) 1, 2, and 3 REASON: ΔH > 0 means that the reaction is endothermic heat energy is on the left side of the equation. Adding solids will not affect equilibrium. Pressure will not affect this equilibrium because there are 4 moles of gas on each side of the equation. Increasing temperature would favor the forward reaction because heat is on the left side. 73. As ice cools from 273 K to 263 K, the average kinetic energy of its molecules will (A) increase (B) decrease (C) remain the same REASON: temperature decreases so the average kinetic energy of its molecules will decrease 74. Which statement describes characteristics of an endothermic reaction? (A) The sign of ΔH is positive, and the products have less potential energy than the reactants. (B) The sign of ΔH is positive, and the products have more potential energy than the reactants. (C) The sign of ΔH is negative, and the products have less potential energy than the reactants. (D) The sign of ΔH is negative, and the products have more potential energy than the reactants. REASON: ΔH > 0 = endothermic reaction, endothermic means that the reaction absorbed energy therefore the products have more potential energy than the reactants. 75. The ability to conduct electricity in the solid state is a characteristic of metallic bonding. This characteristic is best explained by the presence of (A) high ionization energies (B) high electronegativities (C) mobile electrons (D) mobile protons REASON: metallic bonding is associated with mobile electrons ( sea of electrons) 76. The table below shows the temperature, pressure, and volume of five samples. Sample Substance Temp. (K) Pressure (atm) Volume (L) A He 273 1 22.4 B O2 273 1 22.4 C Ne 273 2 22.4 D N2 546 2 44.8 E Ar 546 2 44.8 Which sample contains the same number of molecules as sample A? (A) E (B) B (C) C (D) D REASON: same number of molecules = same volume, same temperature, and same pressure 77. The characteristic bright-line spectrum of an element is produced when its electrons (A) form a covalent bond (B) form an ionic bond
(C) move to a higher energy level (D) return to a lower energy level REASON: bright line spectrum = emission of energy. energy emitted when electrons return to a lower energy level. Back to the Practice Exam Page Back to the Review Material Page Back to the Main Page