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 ___

2. All atoms of a certain element have the same number of protons. True False ___

3. All matter is composed of certain basic substances called elements. True False ___

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 ___

5. Protons have a __________ electrical charge. A. positive B. negative C. neutral ___

6. Electrons always have the same amount of potential energy. True False ___

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 ___

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 ___

9. Electrons with the least amount of potential energy are located in the __________ shell. A. L B. K C. M ___

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 ___

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 ___

12. Electrons that are farther from the nucleus have more potential energy than electrons closer to the nucleus. True False ___

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 ___

14. The nucleus contains ________. A. protons B. electrons C. neutrons D. A and C ___

15. Electron shells, other than the first one, can contain up to eight electrons. True False ___

16. An electrically neutral atom with an atomic number of 7 will have _____ electron shell(s). A. one B. two C. three D. four ___

17. Electrically neutral magnesium (atomic number 12) is an example of an inert (non reactive) atom. True False ___

18. How many carbon atoms are there in a molecule of glucose, C6H12O6? A. 1 B. 6 C. 12 D. 24 ___

19. If a chemical equation is balanced, there are equal numbers of each specific atom on both sides of the arrow. True False ___

20. An atom of hydrogen (atomic number = 1; atomic mass = 1) has one proton and no neutrons. True False ___

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 ___

22. The sodium ion (Na+) has 12 protons (atomic number of Na = 11). True False ___

23. Which bond is most easily broken? A. a hydrogen bond B. a triple covalent bond C. a single covalent bond ___

24. What type of bond is formed when atoms share electrons? A. ionic B. covalent C. hydrogen ___

25. Chlorine (atomic number = 17) needs _____ electron(s) to fill its outermost electron shell. A. no B. one C. seven D. eight ___

26. Electrically neutral atoms are called ions. True False ___

A. single B. double C. triple 27. In a __________ covalent bond, two atoms share two pairs of electrons. A. single B. double C. triple ___

28. An equal sharing of electrons creates a __________ bond. A. polar covalent B. ionic C. hydrogen D. non-polar covalent ___

29. Which of the following is most likely to form an ionic bond with Cl-? A. F- B. Na+ C. He D. O2 ___

30. Which of the following is an example of a compound? A. O2 B. Na+ C. CO2 D. Ne ___

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 ___

32. An atom with one electron in its outermost shell tends to be an electron donor. True False ___

33. A dashed line between atoms represents a(n) _____ bond. A. hydrogen B. single covalent bond C. ionic D. polar covalent bond ___

34. The chlorine ion (Cl-) has 17 protons and 18 electrons. True False ___

35. The three dimensional shape of a molecule affects its ability to function. True False ___

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 ___

37. Energy is __________. A. required for a bond to form B. released when a bond is broken C. A and B ___

38. An attraction between oppositely charged atoms forms a _____ bond. A. polar covalent B. triple covalent C. hydrogen D. ionic ___

39. The atom with greater electronegativity will have a slight positive charge in a polar covalent bond. True False ___

40. Water is a polar molecule. True False ___

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 ___

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 ___

43. Water molecules are _____. A. polar B. hydrogen bonded to one another C. cohesive D. all of the above ___

44. Internal body fluids are kept at a near neutral pH by buffers. True False ___

A. acidic B. basic C. neutral 45. A pH of 7 is _____. A. acidic B. basic C. neutral ___

46. Which of the following has a basic pH? A. lemon juice B. milk of magnesia C. tomatoes D. hydrochloric acid ___

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 ___

48. All living things are _____ water. A. less than 10% B. 10-30% C. 40-60% D. 70-90% ___

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. ___

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. ___

51. Molecules that attract water are described as hydrophilic. True False ___

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). ___

53. Which of the following is best described as hydrophobic? A. water B. oil C. sugar D. salt ___

54. Water would still freeze at 0°C and boil at 100°C without hydrogen bonding. True False ___

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 ___

56. Any pH below _____ is acidic. A. one B. five C. seven D. twelve

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 ___

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 ___

59. Which of the following is an example of an acid? A. HCl B. NaCl C. NaOH D. CO2 ___

60. Water is less dense at 4°C than at 0°C which is why water freezes from the bottom upwards. True False ___