1. Chemical Bonds and Mixtures
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2. How many unpaired valence electrons are there in a nitrogen atom?
One.
Two.
Three.
Five. N
Answer: C) Three.
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3. How many unpaired valence electrons are there in a nitrogen atom?
One.
Two.
Three.
Five. N
Answer: C) Three.
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4. How many bonds is nitrogen able to make?
One.
Two.
Three.
Five. N
Answer: C) Three.
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5. How many bonds is nitrogen able to make?
One.
Two.
Three.
Five. N
Answer: C) Three.
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6. The neon atom tends NOT to gain any additional electrons because
its nuclear charge is not great enough.
that would result in a positive ion.
of the repulsions they would experience with electrons in the same shell.
there is no more room available in its outermost occupied shell.
Answer: D) there is no more room available in its outermost occupied shell.
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7. The neon atom tends NOT to gain any additional electrons because
its nuclear charge is not great enough.
that would result in a positive ion.
of the repulsions they would experience with electrons in the same shell.
there is no more room available in its outermost occupied shell.
Answer: D) there is no more room available in its outermost occupied shell.
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8. Magnesium ions carry a 2+ charge, and chloride ions carry a 1– charge
Magnesium ions carry a 2+ charge, and chloride ions carry a 1– charge. What is the chemical formula for the ionic compound magnesium chloride?
MgCl
Mg2Cl
MgCl2
Mg2Cl2
Answer: C) MgCl2
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9. Magnesium ions carry a 2+ charge, and chloride ions carry a 1– charge
Magnesium ions carry a 2+ charge, and chloride ions carry a 1– charge. What is the chemical formula for the ionic compound magnesium chloride?
MgCl
Mg2Cl
MgCl2
Mg2Cl2
Answer: C) MgCl2
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10. A hydrogen atom does not form more than one covalent bond, because it
has only one shell of electrons.
has only one electron to share.
loses its valence electron so readily.
has such a strong electronegativity.
Answer: B) has only one electron to share.
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11. A hydrogen atom does not form more than one covalent bond, because it
has only one shell of electrons.
has only one electron to share.
loses its valence electron so readily.
has such a strong electronegativity.
Answer: B) has only one electron to share.
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12. An atom loses an electron to another atom
An atom loses an electron to another atom. Is this an example of a physical or a chemical change?
Physical change involving the formation of negative ions.
Chemical change involving the formation of negative ions.
Physical change involving the formation of positive ions.
Chemical change involving the formation of positive ions.
Answer: D) Chemical change involving the formation of positive ions.
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13. An atom loses an electron to another atom
An atom loses an electron to another atom. Is this an example of a physical or a chemical change?
Physical change involving the formation of negative ions.
Chemical change involving the formation of negative ions.
Physical change involving the formation of positive ions.
Chemical change involving the formation of positive ions.
Answer: D) Chemical change involving the formation of positive ions.
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14. Classify the following bond as ionic, covalent, or metallic (Na, atomic number 11; Cl, atomic number 17) Na with Cl Na with Na Cl with Cl
metallic, covalent, covalent
ionic, metallic, covalent
ionic, ionic, covalent
covalent, metallic, ionic
Answer: B) ionic, metallic, covalent
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15. Classify the following bond as ionic, covalent, or metallic (Na, atomic number 11; Cl, atomic number 17) Na with Cl Na with Na Cl with Cl
metallic, covalent, covalent
ionic, metallic, covalent
ionic, ionic, covalent
covalent, metallic, ionic
Answer: B) ionic, metallic, covalent
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16. In terms of the periodic table, is there an abrupt or gradual change between ionic and covalent bonds?
An abrupt change that occurs across the metalloids.
Actually, any element of the periodic table can form a covalent bond.
There is a gradual change: the farther apart, the more ionic.
Whether an element forms one or the other depends on nuclear charge and not the relative positions in the periodic table.
Answer: C) There is a gradual change: the farther apart, the more ionic.
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17. In terms of the periodic table, is there an abrupt or gradual change between ionic and covalent bonds?
An abrupt change that occurs across the metalloids.
Actually, any element of the periodic table can form a covalent bond.
There is a gradual change: the farther apart, the more ionic.
Whether an element forms one or the other depends on nuclear charge and not the relative positions in the periodic table.
Answer: C) There is a gradual change: the farther apart, the more ionic.
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18. Which bond is most polar?
H-N
N-C
C-C
O-H
Answer: D) O-H
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19. Which bond is most polar?
H-N
N-C
C-C
O-H
Answer: D) O-H
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20. Hydrogen chloride, HCl, is a gas at room temperature
Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be very soluble or not very soluble in water?
Very soluble in water by because it is polar.
Not very soluble in water because it is a gas.
Very soluble in water, because it is such a small molecule.
Not very soluble, because it is nonpolar.
Answer: A) Very soluble in water by because it is polar.
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21. Hydrogen chloride, HCl, is a gas at room temperature
Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be very soluble or not very soluble in water?
Very soluble in water by because it is polar.
Not very soluble in water because it is a gas.
Very soluble in water, because it is such a small molecule.
Not very soluble, because it is nonpolar.
Answer: A) Very soluble in water by because it is polar.
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22. Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why?
These atoms are too large to be able to come in close contact with other atoms.
They have a great tendency to lose electrons.
They are on the wrong side of the periodic table.
Their valence shells are already filled with electrons.
Answer: B) They have a great tendency to lose electrons.
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23. Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why?
These atoms are too large to be able to come in close contact with other atoms.
They have a great tendency to lose electrons.
They are on the wrong side of the periodic table.
Their valence shells are already filled with electrons.
Answer: B) They have a great tendency to lose electrons.
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24. How many electrons are used to draw the electron-dot structure for hydrogen peroxide, a covalent compound with the formula H2O2? 14 8 7 4
Answer: A) 14
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25. How many electrons are used to draw the electron-dot structure for hydrogen peroxide, a covalent compound with the formula H2O2? 14 8 7 4 H O O H
Answer: A) 14
[There are two electrons per bond]
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26. The source of an atom's electronegativity is the
kinetic energy which electrons orbiting the nucleus have.
repulsive force occurring among electrons within the same shell.
repulsive force occurring between electrons within neighboring shells.
effective nuclear charge.
Answer: D) effective nuclear charge.
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27. The source of an atom's electronegativity is the
kinetic energy which electrons orbiting the nucleus have.
repulsive force occurring among electrons within the same shell.
repulsive force occurring between electrons within neighboring shells.
effective nuclear charge.
Answer: D) effective nuclear charge.
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28. Two molecules have very different physical properties
Two molecules have very different physical properties. Molecule "A" boils at 80°C and freezes at –30°C. Molecule "B" boils at 35°C and freezes at –100°C. Which molecule is likely to have the largest dipole?
Molecule A
Molecule B
Not enough information was given.
Both have similar dipoles.
Molecule A and molecule B are the same, but each has different properties.
Answer: A) Molecule A
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29. Two molecules have very different physical properties
Two molecules have very different physical properties. Molecule "A" boils at 80°C and freezes at –30°C. Molecule "B" boils at 35°C and freezes at –100°C. Which molecule is likely to have the largest dipole?
Molecule A
Molecule B
Not enough information was given.
Both have similar dipoles.
Molecule A and molecule B are the same, but each has different properties.
Answer: A) Molecule A
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30. Magnesium chloride, MgCl2, crystals are composed of
a two-dimensional array of [-Mg-Cl-Cl-] units.
a multitude of Mg2+ ions and Cl– ions grouped together in a three-dimensional array with a 1:2 ratio of Mg2+ to Cl–.
units of MgCl2 molecules held together by dipole interactions.
groups of Mg2+ ions and Cl2 molecules.
Answer: B) a multitude of Mg2+ ions and Cl– ions grouped together in a three-dimensional array with a 1:2 ratio of Mg2+ to Cl–.
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31. Magnesium chloride, MgCl2, crystals are composed of
a two-dimensional array of [-Mg-Cl-Cl-] units.
a multitude of Mg2+ ions and Cl– ions grouped together in a three-dimensional array with a 1:2 ratio of Mg2+ to Cl–.
units of MgCl2 molecules held together by dipole interactions.
groups of Mg2+ ions and Cl2 molecules.
Answer: B) a multitude of Mg2+ ions and Cl– ions grouped together in a three-dimensional array with a 1:2 ratio of Mg2+ to Cl–.
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32. When nitrogen and fluorine combine to form a molecule, the most likely chemical formula is
N3F
N2F
NF4 NF
NF3
Answer: E) NF3
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33. When nitrogen and fluorine combine to form a molecule, the most likely chemical formula is
N3F
N2F
NF4 NF
NF3 F N F F
Answer: E) NF3
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34. The charges with sodium chloride are all balanced—for every positive sodium ion, there is a corresponding negative chloride ion. Because its charges are balanced, how can sodium chloride be attracted to water, and vice versa?
Dispersion forces come into play.
Hydrogen bonding.
Sodium chloride dissolves in water because water provides a medium in which the individual sodium and chloride ions can disperse.
As a water molecule gets close to the sodium chloride, it can distinguish the various ions.
Answer: D) As a water molecule gets close to the sodium chloride, it can distinguish the various ions.
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35. The charges with sodium chloride are all balanced—for every positive sodium ion, there is a corresponding negative chloride ion. Because its charges are balanced, how can sodium chloride be attracted to water, and vice versa?
Dispersion forces come into play.
Hydrogen bonding.
Sodium chloride dissolves in water because water provides a medium in which the individual sodium and chloride ions can disperse.
As a water molecule gets close to the sodium chloride, it can distinguish the various ions.
Answer: D) As a water molecule gets close to the sodium chloride, it can distinguish the various ions.
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36. Why are ion–dipole attractions stronger than dipole–dipole attractions?
The chemical bond in an ion–dipole molecule is similar to a covalent bond.
Like charge (dipole) does not attract like charge (another dipole).
Dipole areas are subject to changing from positive to negative regions on the molecule.
The magnitude of the electric charge associated with an ion is much greater.
Answer: D) The magnitude of the electric charge associated with an ion is much greater.
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37. Why are ion–dipole attractions stronger than dipole–dipole attractions?
The chemical bond in an ion–dipole molecule is similar to a covalent bond.
Like charge (dipole) does not attract like charge (another dipole).
Dipole areas are subject to changing from positive to negative regions on the molecule.
The magnitude of the electric charge associated with an ion is much greater.
Answer: D) The magnitude of the electric charge associated with an ion is much greater.
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38. Which of the following compounds might best help to make water and gasoline mix into a single liquid phase?
The molecule in the middle—because when the salts mix into the water, it will help separate the water and decrease the attraction for itself.
The molecule on the far left—because the O-H bond is polar, and the carbon and hydrogen bonds are nonpolar.
The molecule on the right will form attractions with the polar ends of the water, allowing the gasoline a chance to mix with the water.
All of these molecules would be equally effective at increasing the mixing of gasoline and water.
Answer: B) The molecule on the far left—because the O-H bond is polar, and the carbon and hydrogen bonds are nonpolar.
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39. Which of the following compounds might best help to make water and gasoline mix into a single liquid phase?
The molecule in the middle—because when the salts mix into the water, it will help separate the water and decrease the attraction for itself.
The molecule on the far left—because the O-H bond is polar, and the carbon and hydrogen bonds are nonpolar.
The molecule on the right will form attractions with the polar ends of the water, allowing the gasoline a chance to mix with the water.
All of these molecules would be equally effective at increasing the mixing of gasoline and water.
Answer: B) The molecule on the far left—because the O-H bond is polar, and the carbon and hydrogen bonds are nonpolar.
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40. Which of the following intermolecular forces best describes why nonpolar molecules like gasoline (C8H18) have only limited solubility in water?
Dipole–dipole.
Induced dipole–induced dipole.
Ion-dipole.
Dipole–induced dipole.
Answer: A) Dipole–dipole.
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41. Which of the following intermolecular forces best describes why nonpolar molecules like gasoline (C8H18) have only limited solubility in water?
Dipole–dipole.
Induced dipole–induced dipole.
Ion-dipole.
Dipole–induced dipole.
Explanation: The strong dipole-dipole attractions among water molecules keep the water molecules from interacting significantly with the nonpolar gasoline molecules.
Answer: A) Dipole–dipole.
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42. Is the air in your house a homogeneous or a heterogeneous mixture?
Homogeneous, because it is mixed very well.
Heterogeneous, because of the dust particles it contains.
Homogeneous, because it is all at the same temperature.
Heterogeneous, because it consists of different types of molecules.
Answer: B) Heterogeneous, because of the dust particles it contains.
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43. Is the air in your house a homogeneous or a heterogeneous mixture?
Homogeneous, because it is mixed very well.
Heterogeneous, because of the dust particles it contains.
Homogeneous, because it is all at the same temperature.
Heterogeneous, because it consists of different types of molecules.
Answer: B) Heterogeneous, because of the dust particles it contains.
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44. Many dry cereals are fortified with iron, which is added in the form of small iron particles. How might these particles be separated from the cereal?
Add water, and the iron particles will float to the top.
Blend the cereal to a fine consistency and pass through a filter.
Collect the iron filings with a magnet.
Heat the cereal so that the iron particles melt and thereby coalesce.
Answer: C) Collect the iron filings with a magnet.
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45. Many dry cereals are fortified with iron, which is added in the form of small iron particles. How might these particles be separated from the cereal?
Add water, and the iron particles will float to the top.
Blend the cereal to a fine consistency and pass through a filter.
Collect the iron filings with a magnet.
Heat the cereal so that the iron particles melt and thereby coalesce.
Answer: C) Collect the iron filings with a magnet.
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46. Would you expect to find more dissolved oxygen in cold polar or warm tropical ocean waters?
Tropical oceans, because intense tropical storms mix up the atmospheric oxygen into the ocean water.
Polar oceans, because the colder oxygen would "sink" and dissolve into the water.
Tropical oceans, because the heated oxygen molecules in the air would collide with and mix into the water.
Polar oceans, because the solubility of oxygen in water decreases with increasing temperature.
Answer: D) Polar oceans, because the solubility of oxygen in water decreases with increasing temperature.
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47. Would you expect to find more dissolved oxygen in cold polar or warm tropical ocean waters?
Tropical oceans, because intense tropical storms mix up the atmospheric oxygen into the ocean water.
Polar oceans, because the colder oxygen would "sink" and dissolve into the water.
Tropical oceans, because the heated oxygen molecules in the air would collide with and mix into the water.
Polar oceans, because the solubility of oxygen in water decreases with increasing temperature.
Answer: D) Polar oceans, because the solubility of oxygen in water decreases with increasing temperature.
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48. Fish don't live very long in water that has just been boiled and brought back to room temperature. Suggest why.
There is now a higher concentration of dissolved CO2 in the water.
The nutrients in the water have been destroyed.
Because some of the water was evaporated while boiling, the salts in the water are now more concentrated. This has a negative effect on the fish.
The boiling process removes the air that was dissolved in the water. Upon cooling, the water is void of its usual air content; hence, the fish drown.
Answer: D) The boiling process removes the air that was dissolved in the water. Upon cooling, the water is void of its usual air content; hence, the fish drown.
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49. Fish don't live very long in water that has just been boiled and brought back to room temperature. Suggest why.
There is now a higher concentration of dissolved CO2 in the water.
The nutrients in the water have been destroyed.
Because some of the water was evaporated while boiling, the salts in the water are now more concentrated. This has a negative effect on the fish.
The boiling process removes the air that was dissolved in the water. Upon cooling, the water is void of its usual air content; hence, the fish drown.
Answer: D) The boiling process removes the air that was dissolved in the water. Upon cooling, the water is void of its usual air content; hence, the fish drown.
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50. How would you respond in defense of water's purity if it contained thousands of molecules of some impurity per glass?
Impurities aren't necessarily bad; in fact, they may be good for you.
The water contains water molecules, and each water molecule is pure.
There's no defense. If the water contains impurities, it should not be drunk.
Compared to the billions and billions of water molecules, a thousand molecules of something else is practically nothing.
Answer: D) Compared to the billions and billions of water molecules, a thousand molecules of something else is practically nothing.
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51. How would you respond in defense of water's purity if it contained thousands of molecules of some impurity per glass?
Impurities aren't necessarily bad; in fact, they may be good for you.
The water contains water molecules, and each water molecule is pure.
There's no defense. If the water contains impurities, it should not be drunk.
Compared to the billions and billions of water molecules, a thousand molecules of something else is practically nothing.
Answer: D) Compared to the billions and billions of water molecules, a thousand molecules of something else is practically nothing.
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52. The boiling point of 1,4-butanediol is 230°C
The boiling point of 1,4-butanediol is 230°C. Would you expect this compound to be soluble or insoluble in room-temperature water?
Insoluble because there are no polar areas on this molecule.
Insoluble because a high boiling point means that the substance interacts with itself quite strongly
Insoluble because there are polar areas on this molecule.
Soluble because there are polar areas on this molecule.
Answer: D) Soluble because there are polar areas on this molecule.
1,4-butanediol
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53. The boiling point of 1,4-butanediol is 230°C
The boiling point of 1,4-butanediol is 230°C. Would you expect this compound to be soluble or insoluble in room-temperature water?
Insoluble because there are no polar areas on this molecule.
Insoluble because a high boiling point means that the substance interacts with itself quite strongly
Insoluble because there are polar areas on this molecule.
Soluble because there are polar areas on this molecule.
Answer: D) Soluble because there are polar areas on this molecule.
1,4-butanediol
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54. What is the molarity of 0.5 liters of a solution with five moles of sucrose in it?
Answer: C) 10 molar
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55. What is the molarity of 0.5 liters of a solution with five moles of sucrose in it?
Answer: C) 10 molar
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56. Account for the observation that ethanol, C2H5OH, mixes readily in water but dimethyl ether, CH3OCH3, which has the same number and kinds of atoms, does not.
The structure of ethanol is less complex.
The ethanol contains a polar O-H bond.
The hydrogens of dimethyl ether shield the inner oxygen from interacting with the water.
Dimethyl ether is a gas and gases do not mix in water.
Answer: B) The ethanol contains a polar O-H bond.
(mixes with water)
(does NOT mix with water)
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57. Account for the observation that ethanol, C2H5OH, mixes readily in water but dimethyl ether, CH3OCH3, which has the same number and kinds of atoms, does not.
The structure of ethanol is less complex.
The ethanol contains a polar O-H bond.
The hydrogens of dimethyl ether shield the inner oxygen from interacting with the water.
Dimethyl ether is a gas and gases do not mix in water.
Answer: B) The ethanol contains a polar O-H bond.
(mixes with water)
(does NOT mix with water)
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58. Which of the following substances should be most soluble in hexane, CH3CH2CH2CH2CH2CH3?
CH3CH2OH
H2O HF
NaCl
Answer: A) I2
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59. Which of the following substances should be most soluble in hexane, CH3CH2CH2CH2CH2CH3?
CH3CH2OH
H2O HF
NaCl
Answer: A) I2
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