True/False Indicate whether the sentence or statement is true or false. |
| 1. | Two atoms having the same number of protons and electrons but different numbers of neutrons are called isotopes. |
| 2. | The nucleus of an atom contains protons and electrons. |
| 3. | A compound consists of atoms of two or more elements joined by chemical bonds. |
| 4. | Energy can be converted from one form to another. |
| 5. | The scale used for measuring the relative concentrations of hydrogen ions and hydroxide ions in a solution is called the pH scale. |
| 6. | Iron atoms and silver atoms have the same number of protons. |
| 7. | An atom containing nine electrons can have three in its first energy level. |
| 8. | Stable atoms need electrons to fill their outer energy levels. |
| 9. | The types of particles that are located in the nucleus of an atom are protons and neutrons, and the types of particles that are located in the energy levels surrounding the nucleus are electrons. |
| 10. | Buffers can neutralize acids, but they do not affect bases. |
Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. |
| 11. | A solution that contains equal concentrations of hydrogen ions and hydroxide ions is a(n): a. | neutral solution | c. | base | b. | acid | d. | compound | | | | |
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| 12. | The type of bond formed when two atoms share electrons is a(n): a. | covalent bond | c. | elemental bond | b. | ionic bond | d. | homogeneous bond | | | | |
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| 13. | Carbon has an atomic number of 6. The number of energy levels in carbon is: |
| 14. | In most elements, how many electrons are in the outer energy level of stable atoms? |
| 15. | A solution with a pH of 9 has: a. | an equal concentration of hydrogen and hydroxide ions | b. | a greater concentration of hydroxide ions than hydrogen ions | c. | a greater concentration of hydrogen ions than hydroxide ions | d. | a greater concentration of hydroxide ions than a solution with a pH of 10 | | |
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| 16. | Carbon 12 and carbon 14 have the same number of protons and electrons, but they differ in the number of neutrons. Therefore, they are: a. | isometric | c. | icicles | b. | isotopes | d. | two different elements | | | | |
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| 17. | How many protons are in an atom that has a mass number of 23 and an atomic number of 11? |
| 18. | Which of the following is matter? a. | oxygen | c. | heat | b. | light | d. | all of these | | | | |
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| 19. | The subscript ‘2’ in H2 represents the number of: a. | electrons | c. | ions | b. | molecules | d. | atoms | | | | |
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| 20. | The smallest unit of a compound that still retains the compound’s unique chemical properties is the: a. | sol | c. | atom | b. | bond | d. | molecule | | | | |
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| 21. | Which of the following best describes a compound? a. | atoms of one element that are chemically combined | b. | two or more elements combined chemically in a definite proportion | c. | atoms of the same element that have different mass numbers | d. | two or more atoms that are not combined chemically | | |
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| 22. | In a covalent bond, electrons are: a. | shared | c. | lost | b. | gained | d. | transferred | | | | |
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| 23. | Which of the following pH values represents the most acidic condition? |
| 24. | The main difference between covalent bonds and ionic bonds is that electrons: a. | are shared in covalent bonds, but not in ionic bonds | b. | are shared in ionic bonds, but not in covalent bonds | c. | are shared in both, but at different times | d. | are involved only in covalent bonds | | |
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| 25. | Which of the following is the most common solvent in organisms? a. | alcohol | c. | water | b. | lipids | d. | amino acids | | | | |
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| 26. | The bond formed when two atoms share a pair of electrons is called a a. | hydrogen bond. | c. | covalent bond. | b. | nonpolar bond. | d. | water bond. | | | | |
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| 27. | The smallest particle of matter that can retain the chemical properties of carbon is a. | a carbon molecule. | c. | a carbon atom. | b. | a carbon macromolecule. | d. | an element. | | | | |
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| 28. | All matter in the universe is composed of a. | cells. | c. | atoms. | b. | molecules. | d. | carbon. | | | | |
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| 29. | Which of the following statements most accurately describes the difference between an ionic bond and a covalent bond? a. | Atoms held together by ionic bonds separate when placed in water while atoms held together by covalent bonds do not separate in water. | b. | Ionic bonds hold together atoms of two different types, while covalent bonds hold together atoms of the same type. | c. | Electrons are exchanged between atoms held together by an ionic bond, but they are shared between atoms held together by a covalent bond. | d. | Ionic bonds form between atoms that carry opposite charges, while covalent bonds form between uncharged atoms. | | |
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| 30. | Refer to the graph above. Reaction “3” in the graph a. | probably occurred in the presence of a catalyst. | b. | requires a greater activation energy than Reaction “2.” | c. | is the same as Reaction “1,” but faster. | d. | takes longer than Reaction “2.” | | |
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| 31. | Changing the course or pathway of a chemical reaction so that it requires less activation energy a. | is a violation of the laws of nature. | b. | requires higher temperatures than those found within cells. | c. | occurs only when reactants are quickly added to the reaction mixture. | d. | is accomplished by the action of catalysts on reactants. | | |
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| 32. | A cell contains a. | thousands of different kinds of enzymes, each promoting a different chemical reaction. | b. | one kind of enzyme that promotes thousands of different chemical reactions. | c. | approximately 100 kinds of enzymes, each promoting a different chemical reaction. | d. | one enzyme that promotes photosynthesis and one enzyme that promotes cellular respiration. | | |
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| 33. | The terms base and alkaline refer to solutions that a. | contain dissolved sodium hydroxide. | b. | contain more hydronium ions than hydroxide ions. | c. | contain more hydroxide ions than hydronium ions. | d. | contain more hydroxide ions than hydrogen ions. | | |
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| 34. | Acidic solutions have a pH that is a. | less than 7. | c. | a negative number. | b. | between 0 and 14. | d. | more than 7. | | | | |
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| 35. | Buffers a. | are of relatively little importance in living things. | b. | are formed when a large number of hydroxide ions are released in a solution. | c. | are formed when a large number of hydronium ions are released in a solution. | d. | tend to prevent great fluctuations in pH. | | |
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