• 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___

•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___

•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___

•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

___

•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___

•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___