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MnO has either a structure like NaCl or a structure like CsCl. The edge length of the MnO unit cell is 4.47 × 10-8 cm, and the density of MnO is 5.28 g/cm3. A. Does MnO crystallize like NaCl or like CsCl? B. If the ionic radius of oxygen is 140. pm, estimate the ionic radius of manganese. C. Does the calculated ratio of the cation radius to the anion radius for MnO support your answer in part A? Explain.

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A. NaCl
B. 83.5 or 84 pm
C. rMn2+/...

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Shown below is a phase diagram for sulfur (not drawn to scale) . Sulfur can exist in solid modifications, rhombic and monoclinic, denoted by SR and SM, respectively. Which of the following statements is incorrect? Shown below is a phase diagram for sulfur (not drawn to scale) . Sulfur can exist in solid modifications, rhombic and monoclinic, denoted by S<sub>R</sub> and S<sub>M</sub>, respectively. Which of the following statements is incorrect? A) At pressures close to 1 atm, rhombic sulfur can be in stable equilibrium with liquid sulfur. B) Under ordinary atmospheric conditions (at sea level) , sulfur does not sublime. C) This system has two triple points. D) At a given pressure, there is (at most) one temperature at which rhombic sulfur can exist in equilibrium with monoclinic sulfur. E) None of these statements is incorrect.


A) At pressures close to 1 atm, rhombic sulfur can be in stable equilibrium with liquid sulfur.
B) Under ordinary atmospheric conditions (at sea level) , sulfur does not sublime.
C) This system has two triple points.
D) At a given pressure, there is (at most) one temperature at which rhombic sulfur can exist in equilibrium with monoclinic sulfur.
E) None of these statements is incorrect.

F) B) and E)
G) A) and C)

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Alkali halides commonly have either the sodium chloride structure or the cesium chloride structure. The molar mass of CsCl is 2.88 times the molar mass of NaCl, and the edge length of the unit cell for NaCl is 1.37 times the edge length of the CsCl unit cell. Determine the ratio of the density of CsCl to the density of NaCl.


A) 0.541
B) 0.984
C) 1.85
D) 1.02
E) 2.10

F) B) and C)
G) B) and D)

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Identify the major attractive force in Cl2.


A) London dispersion forces
B) hydrogen bonding
C) ionic bonding
D) dipole-dipole interactions
E) none of these

F) B) and E)
G) A) and E)

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A metal crystallizes in a body-centered unit cell with an edge length of 2.05 × 102 pm. Assume the atoms in the cell touch along the cube diagonal. What will be the percentage of empty volume in the unit cell?


A) 68.0%
B) 75.5%
C) 0.00%
D) 32.0%
E) 26.0%

F) A) and E)
G) A) and D)

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A certain substance, X, has a triple-point temperature of 20°C at a pressure of 2.0 atm. Which one of the following statements cannot possibly be true?


A) X can exist as a liquid above 20°C.
B) Both liquid and solid X have the same vapor pressure at 20°C.
C) Liquid X can exist as a stable phase at 25°C, 1 atm.
D) X can exist as a solid above 20°C.
E) All of these statements could be true.

F) C) and E)
G) A) and D)

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The triple point of iodine is at 90 torr and 115°C. This means that liquid I2


A) cannot exist above 115°C.
B) cannot exist at 1 atm pressure.
C) can exist at pressure of 10 torr.
D) is more dense than I2(s) .
E) cannot have a vapor pressure less than 90 torr.

F) A) and B)
G) D) and E)

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Shown below is a phase diagram for compound X. How will the melting point of X change with increased pressure? Shown below is a phase diagram for compound X. How will the melting point of X change with increased pressure? A) There is not enough information given. B) It will increase. C) It will increase and then decrease. D) It will decrease. E) It will remain the same.


A) There is not enough information given.
B) It will increase.
C) It will increase and then decrease.
D) It will decrease.
E) It will remain the same.

F) C) and D)
G) B) and C)

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Given the phase diagram shown below, which of the following statements is false? Given the phase diagram shown below, which of the following statements is false? A) When heated at 1 atm, this substance will first melt and then boil. B) When phase A is compressed at constant temperature at point X, no change is observed. C) At some (constant) temperature, the gaseous substance can be compressed into a solid and then into a liquid in this order. D) The solid has a higher density than the liquid. E) None of these statements is false.


A) When heated at 1 atm, this substance will first melt and then boil.
B) When phase A is compressed at constant temperature at point X, no change is observed.
C) At some (constant) temperature, the gaseous substance can be compressed into a solid and then into a liquid in this order.
D) The solid has a higher density than the liquid.
E) None of these statements is false.

F) B) and E)
G) A) and B)

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Mn crystallizes in the same cubic unit cell as Cu. Assuming that the radius of Mn is 5.6% larger than the radius of Cu and that the density of copper is 8.96 g/cm3, calculate the density of Mn.


A) 7.67 g/cm3
B) 8.48 g/cm3
C) 9.46 g/cm3
D) 6.58 g/cm3
E) 9.12 g/cm3

F) D) and E)
G) B) and E)

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The resistance of a liquid to an increase in its surface area is called


A) capillary action.
B) viscosity.
C) surface tension.
D) vapor pressure
E) none of these

F) A) and D)
G) C) and E)

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Given below are the temperatures at which two different liquid compounds with the same empirical formula have a vapor pressure of 400 torr. Given below are the temperatures at which two different liquid compounds with the same empirical formula have a vapor pressure of 400 torr. Which of the following statements is false? A) Increasing the temperature will increase the vapor pressure of both liquids. B) Intermolecular attractive forces are stronger in (liquid) ethanol than in (liquid) dimethyl ether. C) The normal boiling point of dimethyl ether will be higher than the normal boiling point of ethanol. D) The reason why the temperature at which the vapor pressure is 400 torr is higher for ethanol (than for dimethyl ether) is that there is strong hydrogen bonding in ethanol. E) None of these statements is false. Which of the following statements is false?


A) Increasing the temperature will increase the vapor pressure of both liquids.
B) Intermolecular attractive forces are stronger in (liquid) ethanol than in (liquid) dimethyl ether.
C) The normal boiling point of dimethyl ether will be higher than the normal boiling point of ethanol.
D) The reason why the temperature at which the vapor pressure is 400 torr is higher for ethanol (than for dimethyl ether) is that there is strong hydrogen bonding in ethanol.
E) None of these statements is false.

F) A) and B)
G) B) and D)

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The unit cell in this two-dimensional crystal contains __________ Xs and __________ Os. The unit cell in this two-dimensional crystal contains __________ Xs and __________ Os. A) 1, 4 B) 1, 2 C) 2, 1 D) 1, 1 E) 4, 1


A) 1, 4
B) 1, 2
C) 2, 1
D) 1, 1
E) 4, 1

F) C) and E)
G) A) and D)

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Molecular complexity leads to lower viscosity.

A) True
B) False

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In cubic closest-packed solids, what percentage of space is occupied by the spheres?


A) 68.0%
B) 74.0%
C) 52.4%
D) 43.8%
E) none of these

F) B) and E)
G) B) and C)

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How many grams of ice would be melted by the energy obtained as 18.0 g of steam is condensed at 100°C and cooled to 0°C?

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Which of the following statements is true about the vapor pressures of methane (CH4) and ammonia (NH3) ?


A) The vapor pressure of ammonia is less than the vapor pressure of methane because ammonia is nonpolar and methane is polar.
B) The vapor pressure of ammonia is greater than the vapor pressure of methane because ammonia is polar and methane is nonpolar.
C) The vapor pressure of methane is greater than the vapor pressure of methane because methane has more hydrogen bonding than ammonia.
D) The vapor pressure of ammonia is equal to the vapor pressure of methane.
E) None of these statements is true.

F) C) and D)
G) D) and E)

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A liquid placed in a closed container will evaporate until equilibrium is reached. At equilibrium, which of the following statements is not true?


A) Liquid molecules are still evaporating.
B) The number of vapor molecules remains essentially constant.
C) The partial pressure exerted by the vapor molecules is called the vapor pressure of the liquid.
D) The boundary (meniscus) between the liquid and the vapor disappears.
E) All of these statements are true.

F) A) and C)
G) A) and D)

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Based on the phase diagram shown below, which of the following statements are correct? I. Sublimation occurs at a point in the transformation that falls along a straight line from point A to point F. II. C and E represent points where the gas and liquid phases are in equilibrium. III. ΔHvap can be measured at point B. IV. Molecules at point D have a greater average kinetic energy than those at point F. V. The temperature at point E is called the critical temperature of the compound. Based on the phase diagram shown below, which of the following statements are correct? I. Sublimation occurs at a point in the transformation that falls along a straight line from point A to point F. II. C and E represent points where the gas and liquid phases are in equilibrium. III. ΔH<sub>vap</sub> can be measured at point B. IV. Molecules at point D have a greater average kinetic energy than those at point F. V. The temperature at point E is called the critical temperature of the compound. A) II, IV, V B) I, II, IV C) I, III, IV D) II, V E) I, II, III


A) II, IV, V
B) I, II, IV
C) I, III, IV
D) II, V
E) I, II, III

F) B) and E)
G) A) and D)

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Chromium metal crystallizes as a body-centered cubic lattice. If the atomic radius of Cr is 1.25 angstroms, what is the density of Cr metal in grams per cubic centimeter?


A) 2.76 g/cm3
B) 5.52 g/cm3
C) 7.18 g/cm3
D) 3.59 g/cm3
E) 7.81 g/cm3

F) C) and D)
G) None of the above

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