1. A. hydrogen B. nitrogen C. carbon D. iron
1. Which of the following elements is NOT one of the six that make up 98% of most organisms' body weight?
A. hydrogen B. nitrogen C. carbon D. iron
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2. 2. All atoms of a certain element have the same number of protons.
True False
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3. 3. All matter is composed of certain basic substances called elements.
True False
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4. A. electrons B. protons C. neutrons
4. The three isotopes of carbon 12C, 13C and 14C have different numbers of _______?
A. electrons B. protons C. neutrons
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5. 5. Protons have a __________ electrical charge.
A. positive B. negative C. neutral
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6. 6. Electrons always have the same amount of potential energy.
True False
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7. 7. The atomic number of an atom is the same as __________.
A. the atom's mass B. the number of protons the atom has C. the number of neutrons the atom has
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8. 8. If an atom has an atomic number of 17 and an atomic mass of 35, the number of neutrons in its nucleus equals _____.
A. 17 B. 18 C. 35 D. 52
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9. 9. Electrons with the least amount of potential energy are located in the __________ shell.
A. L B. K C. M
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10. 10. If an atom with an atomic number of 9 and an atomic mass of 19 is electrically neutral, it has __________ electrons.
A. 9 B. 10 C. 19 D. 28
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11. 11. Radioactive isotopes are used to __________.
A. determine the age of fossils B. trace chemicals during biochemical reactions C. detect thyroid abnormalities D. all of the above
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12. 12. Electrons that are farther from the nucleus have more potential energy than electrons closer to the nucleus.
True False
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13. A. proton B. electron C. neutron
13. The subatomic particle with an atomic mass of one and a neutral charge is a(n) __________.
A. proton B. electron C. neutron
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14. 14. The nucleus contains ________.
A. protons B. electrons C. neutrons D. A and C
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15. 15. Electron shells, other than the first one, can contain up to eight electrons.
True False
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16. 16. An electrically neutral atom with an atomic number of 7 will have _____ electron shell(s).
A. one B. two C. three D. four
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17. 17. Electrically neutral magnesium (atomic number 12) is an example of an inert (non reactive) atom.
True False
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18. 18. How many carbon atoms are there in a molecule of glucose, C6H12O6?
A. 1 B. 6 C. 12 D. 24
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19. 19. If a chemical equation is balanced, there are equal numbers of each specific atom on both sides of the arrow.
True False
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20. 20. An atom of hydrogen (atomic number = 1; atomic mass = 1) has one proton and no neutrons.
True False
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21. 21. Which of the following is an inert (non-reactive) atom?
A. hydrogen; atomic number = 1 B. oxygen; atomic number = 8 C. neon; atomic number = 10 D. chlorine; atomic number = 17
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22. 22. The sodium ion (Na+) has 12 protons (atomic number of Na = 11).
True False
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23. 23. Which bond is most easily broken?
A. a hydrogen bond B. a triple covalent bond C. a single covalent bond
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24. 24. What type of bond is formed when atoms share electrons?
A. ionic B. covalent C. hydrogen
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25. 25. Chlorine (atomic number = 17) needs _____ electron(s) to fill its outermost electron shell.
A. no B. one C. seven D. eight
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26. 26. Electrically neutral atoms are called ions.
True False
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27. A. single B. double C. triple
27. In a __________ covalent bond, two atoms share two pairs of electrons.
A. single B. double C. triple
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28. 28. An equal sharing of electrons creates a __________ bond.
A. polar covalent B. ionic C. hydrogen D. non-polar covalent
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29. 29. Which of the following is most likely to form an ionic bond with Cl-?
A. F- B. Na+ C. He D. O2
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30. 30. Which of the following is an example of a compound?
A. O2 B. Na+ C. CO2 D. Ne
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31. A. ionic B. triple covalent C. single covalent D. none
31. What type of bond will form between 2 atoms of nitrogen (atomic number = 7) to form the gas N2?
A. ionic B. triple covalent C. single covalent D. none
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32. 32. An atom with one electron in its outermost shell tends to be an electron donor.
True False
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33. 33. A dashed line between atoms represents a(n) _____ bond.
A. hydrogen B. single covalent bond C. ionic D. polar covalent bond
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34. 34. The chlorine ion (Cl-) has 17 protons and 18 electrons.
True False
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35. 35. The three dimensional shape of a molecule affects its ability to function.
True False
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36. 36. Hydrogen bonds form when ___________.
A. atoms share electrons B. a slightly negative atom is attracted to a slightly positive atom C. atoms gain electrons D. atoms lose protons
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37. 37. Energy is __________.
A. required for a bond to form B. released when a bond is broken C. A and B
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38. 38. An attraction between oppositely charged atoms forms a _____ bond.
A. polar covalent B. triple covalent C. hydrogen D. ionic
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39. 39. The atom with greater electronegativity will have a slight positive charge in a polar covalent bond.
True False
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40. 40. Water is a polar molecule. True False
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41. 41. A negative ion _____.
A. has accepted an electron from another atom B. is radioactive and can be used to determine the age of fossils C. will form a polar covalent bond with another atom D. all of the above
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42. 42. The calcium ion (Ca2+) _____.
A. has accepted two protons B. has given away two electrons C. will form a covalent bond with the chlorine ion (Cl-) D. all of the above
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43. 43. Water molecules are _____.
A. polar B. hydrogen bonded to one another C. cohesive D. all of the above
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44. 44. Internal body fluids are kept at a near neutral pH by buffers.
True False
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45. A. acidic B. basic C. neutral
45. A pH of 7 is _____.
A. acidic B. basic C. neutral
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46. 46. Which of the following has a basic pH?
A. lemon juice B. milk of magnesia C. tomatoes D. hydrochloric acid
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47. 47. Hydrogen bonding ___________.
A. causes water molecules to cling to each other B. allows water to absorb a lot of heat without a huge change in temperature C. must be broken to convert water to steam D. all of the above
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48. 48. All living things are _____ water.
A. less than 10% B % C % D %
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49. 49. Which property of water is attributed to its polarity?
A. It resists changes in temperature. B. It has a high surface tension. C. It is the universal solvent. D. It is less dense as a solid than as a liquid.
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50. 50. Which property of water is responsible for facilitating the flow of water upwards in a tree?
A. It resists changes of state (from liquid to ice or liquid to steam). B. It is cohesive and adhesive. C. It is the universal solvent. D. It is less dense as a solid than as a liquid.
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51. 51. Molecules that attract water are described as hydrophilic.
True False
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52. 52. Aquatic living things are able to survive the winter thanks to which property of water?
A. It is less dense as a solid than as a liquid. B. It is cohesive and adhesive. C. It is the universal solvent D. It resists changes of state (from liquid to ice or liquid to steam).
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53. 53. Which of the following is best described as hydrophobic?
A. water B. oil C. sugar D. salt
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54. 54. Water would still freeze at 0°C and boil at 100°C without hydrogen bonding.
True False
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55. 55. A solution with a pH of 5 has 10 times more hydrogen ions (H+) than a solution with a pH of 6.
True False
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56. 56. Any pH below _____ is acidic. A. one B. five C. seven D. twelve

57. 57. Acid rain is a problem because ___________.
A. it adversely affects fish living in lakes B. it weakens trees by leaching away nutrients C. it damages marble and limestone buildings and monuments D. all of the above
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58. 58. Sulfur dioxide and nitrogen oxides combine with atmospheric water to produce sulfuric acid and nitric acid which falls to earth as acid rain.
True False
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59. 59. Which of the following is an example of an acid?
A. HCl B. NaCl C. NaOH D. CO2
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60. 60. Water is less dense at 4°C than at 0°C which is why water freezes from the bottom upwards.
True False
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