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Health Education Systems Admission Assessment Chemistry

Atomic structure, bonding, reactions, solutions, and acids and bases.

These questions are original. This is not an official Health Education Systems Admission Assessment, and FreeExam is not affiliated with Elsevier.

  1. 1.Every atom of carbon has 6 protons. Which number is the atomic number of carbon?

  2. 2.Which particle has no charge and is found in the nucleus?

  3. 3.Which particle has a negative charge and stays outside the nucleus?

  4. 4.A lab card lists a neutral aluminum atom with 13 protons. How many electrons are in that atom?

  5. 5.An atom has 17 protons and 20 neutrons. What is its mass number?

  6. 6.Carbon-12 and carbon-14 have the same number of protons but different numbers of neutrons. What are these two atoms called?

  7. 7.A magnesium atom loses two electrons. What is the charge of the ion that forms?

  8. 8.A chlorine atom gains one electron. What is the charge of the ion that forms?

  9. 9.A neutral atom has 11 protons and 12 neutrons. What is its mass number?

  10. 10.An ion has 17 protons and 18 electrons. What is its charge?

  11. 11.Which description of an atom is correct?

  12. 12.When two atoms bond, which part of each atom is usually gained, lost, or shared?

  13. 13.Oxygen sits in group 16 of the periodic table. How many valence electrons does a neutral oxygen atom have?

  14. 14.In the simple shell model, what is the greatest number of electrons the first shell can hold?

  15. 15.Elements in the same horizontal row of the periodic table belong to the same what?

  16. 16.Sodium and potassium sit one above the other in the first column. They belong to the same what?

  17. 17.Why do elements in the same main group have similar chemical behavior?

  18. 18.Moving down a group, what generally happens to atomic radius?

  19. 19.Moving from left to right across a period, what generally happens to atomic radius?

  20. 20.Moving from left to right across a period, what generally happens to ionization energy?

  21. 21.Neon rarely forms compounds because its outer shell is full. Neon belongs to which family?

  22. 22.Which description fits the alkali metals?

  23. 23.Which description fits the halogens?

  24. 24.Which statement about metals and nonmetals is correct?

  25. 25.Sodium chloride forms when a metal and a nonmetal attract after electrons are transferred. What kind of bond is that?

  26. 26.The two chlorine atoms in a Cl2 molecule are held together by one shared pair of electrons. What is that bond called?

  27. 27.Inside one water molecule, oxygen and hydrogen share electrons unequally. What is each O-H bond?

  28. 28.The attraction between a hydrogen atom of one water molecule and the oxygen atom of a neighboring water molecule is which interaction?

  29. 29.Metal atoms share a mobile sea of valence electrons around positive metal ions. What is that bonding called?

  30. 30.Solid sodium chloride does not conduct electricity, but molten sodium chloride does. Why does the liquid conduct?

  31. 31.At room temperature, carbon dioxide is a gas and sodium chloride is a crystalline solid. Which comparison is sound?

  32. 32.Hydrogen is stable with 2 electrons in its only shell. Many other main-group atoms form bonds to reach how many valence electrons?

  33. 33.A single covalent bond consists of how many shared electrons?

  34. 34.Which element attracts bonding electrons most strongly?

  35. 35.A bond between two atoms with a very large difference in electronegativity is usually which kind?

  36. 36.When sodium and chlorine form NaCl, what happens to the valence electron of sodium?

  37. 37.What is the name of NaCl?

  38. 38.What is the name of MgCl2?

  39. 39.What is the name of Al2O3?

  40. 40.What is the name of K2O?

  41. 41.What is the name of CO2?

  42. 42.What is the name of CO?

  43. 43.What is the name of N2O?

  44. 44.What is the name of SO3?

  45. 45.What is the name of CaCO3?

  46. 46.What is the name of NaOH?

  47. 47.What is the name of Ca(OH)2?

  48. 48.Which formula represents hydrochloric acid?

  49. 49.Which equation correctly shows hydrogen gas and oxygen gas forming water?

  50. 50.Which equation correctly shows nitrogen gas and hydrogen gas forming ammonia?

  51. 51.Which equation correctly shows methane burning in oxygen to form carbon dioxide and water?

  52. 52.Which equation correctly shows iron reacting with oxygen to form iron(III) oxide, Fe2O3?

  53. 53.Which equation correctly shows potassium chlorate, KClO3, breaking down into potassium chloride and oxygen?

  54. 54.Sodium metal and chlorine gas combine: 2 Na + Cl2 → 2 NaCl. What type of reaction is that?

  55. 55.Water is broken down by electrolysis: 2 H2O → 2 H2 + O2. What type of reaction is that?

  56. 56.Zinc metal is placed in hydrochloric acid: Zn + 2 HCl → ZnCl2 + H2. What type of reaction is that?

  57. 57.Silver nitrate solution is mixed with sodium chloride solution: AgNO3 + NaCl → AgCl + NaNO3. What type of reaction is that?

  58. 58.Methane burns completely in plenty of oxygen. Which products form?

  59. 59.A sealed flask contains a chemical reaction. Atoms rearrange into new substances, and nothing enters or leaves. Which quantity stays the same?

  60. 60.In the formula H2O, what does the subscript 2 mean?

  61. 61.A hand-warmer pack gives off heat while its contents react. How is that reaction classified?

  62. 62.A substance speeds a reaction, is still present afterward, and lowers the activation energy. What is that substance called?

  63. 63.Using H = 1 and O = 16, what is the molar mass of water, H2O?

  64. 64.A flask holds 36 g of water. The molar mass of water is 18 g/mol. How many moles of water are in the flask?

  65. 65.Using C = 12 and O = 16, what is the mass of 0.5 mol of carbon dioxide, CO2?

  66. 66.Using Na = 23 and Cl = 35.5, what is the molar mass of sodium chloride, NaCl?

  67. 67.The molar mass of NaCl is 58.5 g/mol. What is the mass of 4 mol of NaCl?

  68. 68.Using Ca = 40, O = 16, and H = 1, what is the molar mass of calcium hydroxide, Ca(OH)2?

  69. 69.Using C = 12 and H = 1, what percent of the mass of methane, CH4, is carbon?

  70. 70.One mole contains 6.02 × 10^23 particles. How many moles are present in 1.204 × 10^24 particles?

  71. 71.Using O = 16, what is the mass of 2 mol of oxygen gas, O2?

  72. 72.A sample contains 3 mol of CO2 molecules. How many moles of oxygen atoms are in that sample?

  73. 73.The balanced equation is 2 H2 + O2 → 2 H2O. How many moles of H2 are needed to react with 3 mol of O2?

  74. 74.The balanced equation is 2 H2 + O2 → 2 H2O, and oxygen is plentiful. How many moles of water form from 4 mol of H2?

  75. 75.Sodium chloride is dissolved in water to make a practice salt solution. In that mixture, what is the sodium chloride?

  76. 76.Which ratio is the definition of molarity?

  77. 77.A solution contains 0.25 mol of solute in 0.50 L of solution. What is its molarity?

  78. 78.How many moles of solute are in 2.0 L of a 0.30 M solution?

  79. 79.Using Na = 23, O = 16, and H = 1, how many grams of NaOH are needed to make 1.0 L of a 0.20 M solution?

  80. 80.A student dilutes 50 mL of a 4.0 M solution to a final volume of 200 mL. What is the new molarity?

  81. 81.A beaker of sugar water holds as much dissolved sugar as it can at that temperature, and a few sugar crystals remain on the bottom. What is that solution called?

  82. 82.Which statement about solubility is the reliable general trend?

  83. 83.What usually happens to the solubility of a gas in water when the water is warmed?

  84. 84.A solution looks uniform throughout, and dissolved particles do not settle. What kind of mixture is it?

  85. 85.Pure water at 25 degrees C has which pH, and how is that value classified?

  86. 86.A student tests a sour lab sample, and the meter shows pH 2. Which term fits that reading?

  87. 87.Household ammonia water gives a meter reading of pH 10. Which term fits that reading?

  88. 88.Two solutions are compared. Solution A has a lower pH than solution B. Which comparison of hydrogen ion concentration is correct?

  89. 89.A solution changes from pH 4 to pH 3. What happens to the hydrogen ion concentration?

  90. 90.A solution changes from pH 6 to pH 8. What happens to the hydrogen ion concentration?

  91. 91.HCl donates H+ to water. In the Bronsted-Lowry sense, HCl is acting as what?

  92. 92.Ammonia accepts a proton from water. In the Bronsted-Lowry sense, ammonia is acting as what?

  93. 93.A dilute solution of HCl is still called a strong acid. Why?

  94. 94.Acetic acid ionizes only partly in water. How is it classified?

  95. 95.Hydrochloric acid is neutralized by sodium hydroxide. Which products form?

  96. 96.A solution has a hydrogen ion concentration of 1 × 10^−5 M. What is its pH?

  97. 97.Which description fits a solid?

  98. 98.Which description fits a liquid?

  99. 99.Which description fits a gas?

  100. 100.The change from a solid to a liquid is called what?

  101. 101.The change from a gas to a liquid is called what?

  102. 102.Solid carbon dioxide, dry ice, changes directly into carbon dioxide gas. What is that change called?

  103. 103.Water vapor turns directly into frost on a cold window, and no liquid appears. What is that change called?

  104. 104.At constant temperature, a trapped gas is squeezed into a smaller volume. What happens to its pressure?

  105. 105.A gas has a pressure of 2 atm and a volume of 6 L. At the same temperature, the volume becomes 3 L. What is the new pressure?

  106. 106.At constant pressure, a gas is heated until its kelvin temperature doubles. What happens to its volume?

  107. 107.A gas occupies 2 L at 300 K. The pressure stays constant while the gas is warmed to 450 K. What is the new volume?

  108. 108.A gas-law problem gives a temperature of 27 degrees C. Before that temperature is used in Charles's law, it must be converted to which scale?