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1. Probes indicating that there is a dry lake bed and trapped water beneath the poles on Mars are of major significance because they suggest that
2. The part of the atom that determines how the atom behaves chemically is the
3. Which component of an atom does not significantly add to the mass of an atom?
4. What is the difference between an atom and an element?
a. An atom is made of protons, electrons, and sometimes neutrons; an element is a substance composed of only one kind of atom.
5. The number of protons in an atom equals the number of
6. Which of the following statements about atoms is true?
c. When protons equal electrons, an atom has a neutral charge.
7. 3115P and 3215P have virtually identical chemical and biological properties because they have the same
e. number of electrons.
8. An atom that is neutrally charged contains
d. the same number of positive particles as negative particles.
9. Phosphorus has an atomic number of 15 and an atomic weight of 30.974. How many neutrons does phosphorus have?
10. The atomic number of an element is the same as the number of _______ in each atom.
11. The number of different elements found in the universe is closest to
12. The best reference source for the atomic number and mass number of elements is
13. Which of the following elements is contained by all living things?
d. Carbone. All of the above
14. Which of the following pairs has similar chemical properties?
d. 12C and 14C
15. The four elements most common in organisms are
c. carbon, oxygen, hydrogen, and nitrogen.
16. Because atoms can have the same number of protons but a different number of neutrons, elements have
17. An element has a weight of 131.3. The reason the number is not a whole number is that
b. atomic weight is the average of the mass numbers of all the element’s isotopes.
18. Why is the atomic weight of hydrogen 1.008 and not exactly its mass number, 1.000?
b. Atomic weight is the average of the mass numbers of a representative sample of the element, including all its isotopes.
19. The mass number of an atom is determined primarily by the _______ it contains.
d. sum of the number of protons and neutrons
20. Hydrogen, deuterium, and tritium all have the same
21. Of the following atomic configurations, the one that has an atomic mass of 14 is the atom with
22. The ability of atoms to combine with other atoms is determined by
b. the number and distribution of electrons.
23. Phosphorus has an atomic number of 15 and an atomic weight of 30.974. From this information it can be determined that this element
a. has isotopes.
24. The atomic mass of an element is the same as the number of _______ in each atom.
d. protons plus neutrons
25. Which of the following elements is the most chemically reactive?
26. When magnesium (Mg) bonds with another element, you would expect that it would
c. lose two electrons to the other element.
27. All of the elements listed below follow the octet rule except
28. Which of the following statements about the difference between ionic bonds and covalent bonds is true?
b. Electron sharing is more equal in the covalent bond.
29. Which of the following is the correct order (in decreasing order) for the relative strengths of chemical bonds?
a. Covalent, ionic, hydrogen, van der Waals forces
30. In a hydrogen molecule, the two atoms are held together by
b. a shared pair of electrons.
31. What determines if a molecule is polar, nonpolar, or ionic?
c. The differences in the electronegativities of the atoms
32. A single covalent chemical bond represents the sharing of how many electrons?
33. All of the following are nonpolar except
34. Two atoms are held together in four covalent bonds because of forces between the
35. Two carbon atoms held together in a double covalent bond share _______ electron(s).
36. Which of the following atoms usually has the greatest number of covalent bonds with other atoms?
37. Oxygen forms _______ bond(s), carbon forms _______, and hydrogen forms _______.
d. two; four; one
38. A covalent bond is the sharing of _______ between atoms, whereas an ironic bond is the _______.
e. electrons; transfer of electrons from one atom to another
39. Chemical bonds formed by electrical attractions are
40. Ionic bonds are
a. attractions between oppositely charged ions.
41. Particles having a net negative charge are called
42. Which of the following molecules is held together primarily by ionic bonds?
43. Hydrogen bonds
c. form between a strong electronegative atom and hydrogen.
44. Cholesterol is composed primarily of carbon and hydrogen atoms. Therefore, one would expect cholesterol to be
a. insoluble in water.
45. A van der Waals interaction is an attraction between
a. the electrons of a nonpolar molecule and the nucleus of a nearby nonpolar molecule.
46. In addition to covalent and ionic bonds, which of the following interactions are important in biological systems?
van der Waals interactions
b. Hydrogen bonds
c. Hydrophobic interactions
d. Both a and b
e. All of the above
47. The hydrogen bond between two water molecules arises because water is
48. Which of the following correctly states an unusual property of water?
e. The hydrogen bonds between water molecules continually form and break.
49. Two characteristics of water make it different from most other compounds: Its solid state is _______ its liquid state and it takes up _______ heat to change to its gaseous state.
a. less dense than; large amounts of
50. Sweating is a useful cooling device for humans because water
a. takes up a great deal of heat in changing from its liquid state to its gaseous state.
51. When exposed to extreme heat, the human body relies on _______ to absorb excess calories of heat and maintain normal body temperature.
52. Which characteristic of water contributes to the relatively constant temperatures of the oceans?
e. It takes a large amount of heat energy to raise the temperature of water.
53. Ice floats because
a. the crystal takes up more space than the liquid.
54. Ice is used in beverages because
e. it absorbs a lot of heat when it melts.
55. If you place a paper towel in a dish of water, the water will move up the towel by capillary action because water
d. can form hydrogen bonds.
56. Surface tension and capillary action occur in water because it
c. has hydrogen bonds.
57. The molecular weight of water is 18.0154. One mole of water weighs exactly _______ grams.
58. When sodium hydroxide (NaOH) is added to water, it ionizes, releasing OH– and Na+ ions. The resulting solution is
59. H2SO4 can ionize to yield two H+ ions and one SO42– ion. H2SO4 is
e. an acid.
60. Which contains more molecules, a mole of hydrogen or a mole of carbon?
c. Both contain the same number of molecules.
61. The difference between an acid and a base is that an acid _______, whereas a base _______.
e. releases H+ ions in solution; accepts H+ ions
62. To determine the number of molecules in a teaspoon of sugar you need to know
e. the weight and molecular weight of the sugar, and Avogadro’s number.
63. How would you make 100 ml of an aqueous solution with a 0.25 M concentration of a compound that has a molecular weight of 200 daltons?
e. Take 5 grams of the compound and add water until the volume equals 100 ml.
64. Of the following compounds containing 1H, 12C, and 16O, the one with the greatest number of molecules in a sample with a mass of 2 grams would be
65. A basic solution contains
a. more OH– ions than H+ ions.
66. A 1.0 M solution of HCl has a pH of
67. The pH 6.0 contains
e. 10–6 moles of hydrogen ions.
68. The more acidic of two solutions has
c. more H+ ions per liter.
69. Solutions that contain buffers tend to resist pH changes because buffers
c. change from nonionic to ionic in response to changes in pH and release or absorb H+.
70. Acid rain is a serious environmental problem. A sample of rainwater collected in the Adirondack Mountains had an H+ concentration of 10–4 mol/L. The pH of this sample was
71. Carbonic acid and sodium bicarbonate act as buffers in the blood. When a small amount of acid is added to this buffer, the H+ ions are used up as they combine with the bicarbonate ions. When this happens, the pH of the blood
c. does not change.
72. The notation [H+] refers to the
d. concentration of H+ ions in moles per liter.
73. Which of the following has the greatest concentration of hydrogen ions?
e. Cola at pH 3
74. The optimum pH for growing strawberries is 6.5, whereas the optimum pH for growing blueberries is 4.5. Therefore, the number of hydrogen ions needed to grow strawberries is _______ times the number needed for blueberries.
1. One dalton is the same as the mass of one _______.
2. Every atom except for _______ has one or more neutrons in its nucleus.
3. Oxygen and carbon are defined as different elements because they have atoms with a different number of _______.
4. The sum of the atomic weights in any given molecule is called its _______.
5. The chemical properties of an element are determined by the number of _______ its atoms contain.
6. _______ occurs when one atom, such as 14C, is transformed into another atom, such as 14N, with an accompanying emission of energy.
7. The tendency of atoms in stable molecules to have eight electrons in their outermost shells is known as the _______.
8. A _______ is two or more atoms linked by chemical bonds.
10. The electronegativity of an atom depends upon the number of _______ and how far the _______ are from the nucleus.
11. Molecules that have an unequal distribution of electric charge are called _______ molecules.
12. Of the different types of chemical bonds, the strongest bond in biological systems is the _______ bond.
13. The attraction between a slight positive charge on a hydrogen atom and the slight negative charge of a nearby electronegative atom is a _______.
14. In the equation, C6H12O6 Æ 6CO2 + 6H2O, C6H12O6 is the _______.
15. The water strider skates along the surface of water due to a property of liquids called _______.
16. The calories needed to raise one gram of a substance 1°C is known as _______.
17. One mole of a substance contains 6.02 ¥ 1023 molecules. This number is known as_______.
18. A chemical reaction that can proceed in either direction is called a _______.
9. The molecular weight of glucose (C6H12O6) is _______.
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