Download Sample Midterm Exam Chemistry 241 R.H. Langley Choose the best

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

Hydroformylation wikipedia , lookup

Evolution of metal ions in biological systems wikipedia , lookup

Metalloprotein wikipedia , lookup

Transcript
Sample Midterm Exam
Chemistry 241
R.H. Langley
Choose the best answer.
_____ 1. The "Law of Octaves" was developed by
A.
B.
C.
D.
E.
Rutherford.
Lavoisier.
Dalton.
Newlands.
None of the above.
_____ 2. The use of atomic numbers for the periodic table was due to work by
A.
B.
C.
D.
E.
Mendeleev.
Meyer.
Rutherford.
Newlands.
None of the above.
_____ 3. The two subdivisions of the inner transition elements are the
A.
B.
C.
D.
E.
f block metals and the actinides.
lanthanides and the heavy lanthanides.
lanthanides and the actinides.
chalcogens and the pctnides.
None of the above.
_____ 4. On the periodic table the largest atoms in a particular family are usually
A.
B.
C.
D.
E.
towards the top.
towards the bottom.
at either end.
in the middle.
None of the above.
_____ 5. The "Uniqueness Principle" applies to all the following elements except
A.
B.
C.
D.
E.
the lanthanides.
hydrogen and helium.
the second period elements.
the first transition series.
None of the above.
_____ 6. In general, an atom with a high electron affinity
A.
B.
C.
D.
E.
has a low ionization energy.
has a high ionization energy.
has a large atomic radius.
is a metal.
None of the above.
_____ 7. The similarity between the properties of zinc and tin is attributed to
A.
B.
C.
D.
E.
the "knight's Move" relationship.
the inert pair effect.
the uniqueness principle.
the diagonal relationship.
None of the above.
_____ 8. Hydrogen is
A.
B.
C.
D.
E.
the tenth most abundant element in the Earth's crust.
the most abundant element in the Earth's crust.
more abundant than oxygen in the Earth's crust.
not present in the Earth's crust.
None of the above.
_____ 9. The product of the radioactive decay of tritium is
A.
B.
C.
D.
E.
helium-3.
helium-4.
alpha particles.
deuterium.
None of the above.
_____ 10. The constant for the autoionization of water (Kw)
A.
B.
C.
D.
E.
decreases with increasing temperature.
is a maximum at room temperature (25°C).
is 1 x 10-14 at all temperatures.
increases with increasing temperature.
None of the above.
_____ 11. Hydrogen bonding is not an important intermolecular force in
A.
B.
C.
D.
E.
CH3CH2OH.
HF.
CH3F
CH3NHCH3.
None of the above.
_____ 12. The hydrogen molecule
A.
B.
C.
D.
E.
is a very weak acid.
is non-acidic.
has hydrogen bonding.
is a strong acid.
None of the above.
_____ 13. Of the following, the strongest acid would be
A.
B.
C.
D.
E.
HXO42- .
H2XO4-.
H3XO4.
XO43-.
None of the above.
_____ 14. Rubidium is most abundant in
A.
B.
C.
D.
E.
potassium minerals.
cesium minerals.
radioactive minerals.
barium minerals.
None of the above.
_____ 15. The two least abundant alkali metals (excluding francium) in the Earth's crust are
A.
B.
C.
D.
E.
lithium and sodium.
lithium and cesium.
sodium and potassium.
potassium and rubidium.
None of the above.
_____ 16. The alkali metal that reacts with nitrogen gas is
A.
B.
C.
D.
E.
lithium.
potassium.
rubidium.
cesium.
None of the above.
_____ 17. The alkali metals may have which oxidation state(s) in their compounds.
A.
B.
C.
D.
E.
+1 or +2.
+1.
+1 or -1.
-1.
None of the above.
_____ 18. Lithium reacts with oxygen to produce
A.
B.
C.
D.
E.
the oxide.
the oxides and the superoxide.
the peroxide and the superoxide.
the oxide, the peroxide, and the superoxide.
None of the above.
_____ 19. The industrial preparation of sodium silicate, NaSiO3, utilizes
A.
B.
C.
D.
E.
the reaction of sodium metal with silicon in the presence of air.
the reaction of sodium oxide with silicon dioxide.
the reaction of sodium peroxide with silicon dioxide.
the electrolysis of aqueous sodium carbonate using a silicon electrode.
None of the above.
_____ 20. The Solvay Process is the major industrial process for producing sodium carbonate
A.
B.
C.
D.
E.
in the United States.
worldwide.
in North America.
in countries other than the United States.
None of the above.
_____ 21. Na5P3O10 is
A.
B.
C.
D.
E.
sodium trimetaphosphate.
pentasodium triphosphate.
sodium tripolyphosphate.
sodium phosphate.
None of the above.
_____ 22. One unusual aspect of the structure of methyllithium is that the
A.
B.
C.
D.
E.
carbon atoms have seven bonds.
compound is ionic.
is dimeric.
compound is unreactive.
None of the above.
_____ 23. The alkali metals will dissolve in liquid ammonia to give
A.
B.
C.
D.
E.
Grignard reagents.
alkali metal anions.
oxidizing solutions.
blue solutions.
None of the above.
_____ 24. Radium occurs primarily in
A.
B.
C.
D.
E.
beryllium ores.
radium minerals.
uranium ores.
calcium ores.
None of the above.
_____ 25. The solution to temporary hardness in water is
A.
B.
C.
D.
E.
precipitating the calcium as the sulfate.
precipitating the magnesium as the phosphate.
freezing.
adding alum.
None of the above.
_____ 26. The major methods for the production of magnesium include
A.
B.
C.
D.
E.
the electrolysis of molten magnesium chloride.
the electrolysis of aqueous magnesium chloride.
the electrolysis of molten magnesium oxide.
heating magnesium oxide with carbon.
None of the above.
_____ 27. The preparative industrial methods for the alkaline earth metals include heating the
metal oxides
A.
B.
C.
D.
E.
with iron.
with lead.
with sulfur.
with iodine.
None of the above.
_____ 28. One of the major industrial chemicals is calcium chloride. This material is
usually prepared
A.
B.
C.
D.
E.
by burning calcium metal in chlorine gas.
by the oxidation of calcium sulfide with chlorine gas.
by the electrolysis of aqueous calcium chlorate.
by the reduction of calcium perchlorate.
None of the above.
_____ 29. Grignard reagents contain
A.
B.
C.
D.
E.
alumminum.
beryllium.
calcium.
magnesium.
None of the above.
_____ 30. Organometallics of the alkaline earth metals
A.
B.
C.
D.
E.
are ionic.
are covalent for beryllium and magnesium, and ionic for the others.
are covalent.
are known for only beryllium and magnesium.
None of the above.
_____ 31. During fluoridation the material in teeth
A.
B.
C.
D.
E.
is changed to calcium fluoride.
has hydroxide ion replaced by fluoride ion.
is coated with fluoride ion.
has phosphate ion replaced by fluoride ion.
None of the above.
_____ 32. Magnesium is necessary for
A.
B.
C.
D.
E.
blood clotting.
lactation.
extracellular enzyme activity.
hormone release.
None of the above.
_____ 33. Strontium compounds
A.
B.
C.
D.
E.
are very dangerous.
are used in various medicines.
are too insoluble to pose a health risk.
have a salty taste.
None of the above.
_____ 34. Radium may.
A.
B.
C.
D.
E.
not be a health risk.
replace barium in enzymes.
replace calcium in bones.
precipitate in the body as radium sulfate.
None of the above.
_____ 35. The element Mendeleev predicted as ekaaluminum is
A.
B.
C.
D.
E.
B.
In.
Tl.
Ga.
None of the above.
_____ 36. Which of the following is not true about thallium?
A.
B.
C.
D.
E.
It occurs in nature primarily as the oxide.
It is found with lead.
It is found with zinc.
It has two stable oxidation states.
None of the above.
_____ 37. Thallium(III) hydroxide
A.
B.
C.
D.
E.
is acidic.
is basic.
is amphoteric.
is neutral.
None of the above.
_____ 38. Gallium is unusual because
A.
B.
C.
D.
E.
it has a very high melting point.
it expands on freezing.
it floats on water.
it is less metallic than aluminum.
None of the above.
_____ 39. Electrolysis of aqueous solutions is important in the industrial preparation of
A.
B.
C.
D.
E.
aluminum.
aluminum and gallium.
aluminum and thallium.
aluminum, gallium, indium, and thallium.
None of the above.
_____ 40. Brønsted Lowry acid base theory is a subdivision of
A.
B.
C.
D.
E.
Arrhenius acid base theory.
Lux-Flood acid base theory.
Amphoteric acid base theory.
Nernst acid base theory.
None of the above.
_____ 41. The bonding in the boron hydrides was first explained by
A.
B.
C.
D.
E.
Pauling.
Lewis.
Brown.
Cotton.
None of the above.
_____ 42. The simplest stable boron hydride is
A.
B.
C.
D.
E.
BH3.
BH4.
B2H6.
BH.
None of the above.
_____ 43. Borosilicates are important
A.
B.
C.
D.
E.
to the semiconductor industry.
to the petroleum industry.
to the automobile industry.
to the computer industry.
None of the above.
_____ 44. Toxic thallium are easily detectible because of
A.
B.
C.
D.
E.
their burning taste.
their salty taste.
their pungent odor.
their sweet odor.
None of the above.
_____ 45. The element in the carbon family with the lowest melting point is
A.
B.
C.
D.
E.
carbon.
tin.
germanium.
lead.
None of the above.
_____ 46. Other than lead, each of the members of the carbon family has an allotrope with
A.
B.
C.
D.
E.
the graphite structure.
a body centered cubic structure.
the diamond structure.
a hexagonal closest packed structure.
None of the above.
_____ 47. The carbon family element(s) not known since ancient times is(are)
A.
B.
C.
D.
E.
germanium.
silicon and lead.
silicon and germanium.
germanium and tin.
None of the above.
_____ 48. Most of the carbon minerals are
A.
B.
C.
D.
E.
carbides.
silicates.
halides.
silicides.
None of the above.
_____ 49. Heating coal in the absence of air produces
A.
B.
C.
D.
E.
charcoal.
graphite.
carbon black.
coke.
None of the above.
_____ 50. Industrially, most tin is prepared by
A.
B.
C.
D.
E.
electrolysis.
reduction of the oxide with lead.
oxidation of tin ore.
pyrolysis of tin ore.
None of the above.
_____ 51. The carbon family element(s) that is(are) important semiconductor(s)
A.
B.
C.
D.
E.
are silicon, germanium, and tin.
is germanium.
is silicon.
are silicon and germanium.
None of the above.
_____ 52. A p-n junction may serve as
A.
B.
C.
D.
E.
an LED.
a transistor.
a rectifier.
a laser.
None of the above.
_____ 53. Carbon monoxide is important to the purification of
A.
B.
C.
D.
E.
aluminum.
silicon.
carbon.
nickel.
None of the above.
_____ 54. Prussic acid is an old name for
A.
B.
C.
D.
E.
cyanogen.
cyanic acid.
hydrocyanic acid.
cyanous acid.
None of the above.
_____ 55. Which of the following is a pseudohalogen?
A.
B.
C.
D.
E.
carbon monoxide.
cyanogen.
carbon dioxide.
chlorine.
None of the above.
_____ 56. Interstitial carbides are
A.
B.
C.
D.
E.
very soft.
very hard.
ionic.
unstable.
None of the above.
_____ 57. The two known covalent carbides contain carbon covalently bonded to
A.
B.
C.
D.
E.
boron or nitrogen.
boron or silicon.
silicon or germanium.
beryllium or boron.
None of the above.
_____ 58. One of the Freons is
A.
B.
C.
D.
E.
CHClF2 .
CH2Cl2.
CHF3.
CF4.
None of the above.
_____ 59. Natural carbon-14
A.
B.
C.
D.
E.
is produced by the interaction of atmospheric nitrogen with cosmic rays.
is produced by the radioactive decay of oxygen-14.
is produced by the radioactive decay of uranium.
is produced by the radioactive decay of boron-14.
None of the above.
_____ 60. The oxidation state of silicon in stable silicon compounds is rarely +2, and usually
A.
B.
C.
D.
E.
+4.
-4.
±4.
-2.
None of the above.
_____ 61. When silicon forms a π bond, it is usually between
A.
B.
C.
D.
E.
two p orbitals.
a p and a d orbital.
two d orbitals.
an s and a d orbital.
None of the above.
_____ 62. Silicon dioxide is
A.
B.
C.
D.
E.
a neutral oxide.
an amphoteric oxide.
a basic oxide.
an acidic oxide.
None of the above.
_____ 63. Pyrosilicates contain
A.
B.
C.
D.
E.
Si2O76-.
SiO44-.
Si2O52-.
(SiO32-)x.
None of the above.
_____ 64. Stishovite
A.
B.
C.
D.
E.
indicates meteorite impacts.
forms at low pressure.
is another name for quartz.
is a phyllosilicate.
None of the above.
_____ 65. Which carbon family element is in pewter?
A.
B.
C.
D.
E.
carbon.
germanium.
lead.
tin.
None of the above.
_____ 66. Silicon
A.
B.
C.
D.
E.
is a nonessential element.
is nearly as toxic as lead.
is an essential trace element.
influences the formation of ATP.
None of the above.
_____ 67. The major industrial method for the production of nitrogen is
A.
B.
C.
D.
E.
fractional distillation of air.
decomposition of nitrates.
decomposition of azides.
isolation from wells.
None of the above.
_____ 68. The major industrial method for the preparation of phosphorus is
A.
B.
C.
D.
E.
the thermal decomposition of phosphine.
the reduction of calcium phosphate with silicon dioxide and carbon.
the electrolysis of aqueous sodium phosphate.
the reduction of calcium phosphate with hydrogen.
None of the above.
_____ 69. The only form of phosphorus soluble in carbon disulfide is
A.
B.
C.
D.
E.
red.
black.
white.
green.
None of the above.
_____ 70. Black phosphorus forms
A.
B.
C.
D.
E.
at high temperatures.
at low temperatures.
at low pressures.
at STP.
None of the above.
_____ 71. The major industrial method for the synthesis of ammonia is
A.
B.
C.
D.
E.
the Haber-Bosch process.
the Ostwald process.
the Frasch process.
the Hall process.
None of the above.
_____ 72. In liquid ammonia, the pH of a neutral solution is about
A.
B.
C.
D.
E.
15.
0.
7.
30.
None of the above.
_____ 73. Weak acids may
A.
B.
C.
D.
E.
become strong acids in liquid ammonia.
become unstable in liquid ammonia.
become bases in liquid ammonia.
become oxidizing agents in liquid ammonia.
None of the above.
_____ 74. The amide ion is
A.
B.
C.
D.
E.
a weak base.
a weak acid.
too strong of a base to exist in water.
able to precipitate potassium ions from solution.
None of the above.
_____ 75. The gas produced in air bags is
A.
B.
C.
D.
E.
NO.
NH3.
N2O.
N2.
None of the above.
_____ 76. The major industrial process for the preparation of nitric acid is
A.
B.
C.
D.
E.
the reaction of dinitrogen pentoxide with water.
the reaction of nitrogen dioxide with water.
the reaction of dinitrogen trioxide with water.
the reaction dinitrogen oxide with water.
None of the above.
_____ 77. Nitric acid
A.
B.
C.
D.
E.
decomposes sulfuric acid to release sulfur trioxide.
is stronger than sulfuric acid.
is the same strength as sulfuric acid.
is weaker than sulfuric acid.
None of the above.
_____ 78. The compound hypophosphorus acid H3PO2, is
A.
B.
C.
D.
E.
a monoprotic acid.
a diprotic acid.
not really an acid.
a strong oxidizing agent.
None of the above.
_____ 79. Phosphate groups may condense to form
A.
B.
C.
D.
E.
polyphosphates and metaphosphates.
metaphosphates.
cyclic phosphates.
orthophosphates.
None of the above.
_____ 80. ATP is an example of a
A.
B.
C.
D.
E.
metaphosphate.
polyphosphate.
orthophosphate.
acid phosphate.
None of the above.
_____ 81. Nearly all bismuth chemistry involves
A.
B.
C.
D.
E.
the -3 oxidation state.
the +3 oxidation state.
either the +1 or the +3 oxidation state.
the +5 oxidation state.
None of the above.
_____ 82. The form of phosphorus that is toxic is
A.
B.
C.
D.
E.
white.
red.
green.
black.
None of the above.
_____ 83. The standard reduction potentials indicate that oxygen is an oxidizing agent and
A.
B.
C.
D.
E.
the other chalcogens are reducing agents.
the other chalcogens are also reducing agents.
the other chalcogens are neither oxidizing nor reducing agents.
the other chalcogens are unreactive.
None of the above.
_____ 84. The chalcogens known for the longest time is
A.
B.
C.
D.
E.
sulfur.
oxygen.
tellurium.
selenium.
None of the above.
_____ 85. Polonium is
A.
B.
C.
D.
E.
a nonmetal.
a metalloid.
a metal.
common.
None of the above.
_____ 86. Ozone is
A.
B.
C.
D.
E.
neither oxidizing nor reducing.
a stronger oxidant than O2.
a stronger reductant than O2.
a weak oxidant than O2.
None of the above.
_____ 87. Oxygen has a positive oxidation state in
A.
B.
C.
D.
E.
HOF.
OF2.
CsO3.
H2O2.
None of the above.
_____ 88. The compound Mn2O7 is
A.
B.
C.
D.
E.
a basic oxide.
an amphoteric oxide.
a strong reducing agent.
a refractory oxide.
None of the above.
_____ 89. The element with the most known allotropes is
A.
B.
C.
D.
E.
oxygen.
sulfur.
selenium.
tellurium.
None of the above.
_____ 90. The peroxydisulfate ion is
A.
B.
C.
D.
E.
a weak oxidizing agent.
a powerful oxidizing agent.
a weak reducing agent.
a powerful reducing agent.
None of the above.
_____ 91. The compound H6TeO6 is
A.
B.
C.
D.
E.
a monoprotic acid.
not an acid.
a hexaprotic acid.
a triprotic acid.
None of the above.
_____ 92. The element with the highest electron affinity is
A.
B.
C.
D.
E.
fluorine.
bromine.
chlorine.
iodine.
None of the above.
_____ 93. Iodine
A.
B.
C.
D.
E.
was first found with astatine.
was first discovered in ancient times.
was discovered by accident.
was first produced by electrolysis.
None of the above.
_____ 94. Bromine
A.
B.
C.
D.
E.
is produced by the oxidation of the bromide ion with elemental iodine.
is produced by electrolysis.
is produced by the oxidation of the bromide ion with elemental bluorine.
is produced by the oxidation of the bromide ion with elemental chlorine.
None of the above.
_____ 95. The only common acid that will attack glass is
A.
B.
C.
D.
E.
HI.
HCl.
HF.
HOF.
None of the above.
_____ 96. The hydrogen halides that may be produced from the action of sulfuric acid on halide
salts are
A.
B.
C.
D.
E.
HBr and HI.
HCl, HBr, and HI.
HF, HCl, and HBr.
HF and HCl.
None of the above.
_____ 97. The strongest hypohalous acid is
A.
B.
C.
D.
E.
HClO.
HBrO.
HIO.
HOF.
None of the above.
_____ 98. The lack of iodine in the diet leads to
A.
B.
C.
D.
E.
depression.
pellagra.
rickets.
anemia.
None of the above.
_____ 99. Helium was first found
A.
B.
C.
D.
E.
in uranium ore.
in the Sun.
in natural gas wells.
in alpha particles.
None of the above.
_____ 100. Radioactive dating methods may use
A.
B.
C.
D.
E.
helium and neon.
argon and krypton.
xenon and helium.
argon and neon.
None of the above.
_____ 101. A clathrate is
A.
B.
C.
D.
E.
the first type of true noble gas compound.
a mythical compound.
formed by the reaction of xenon with platinum hexafluoride.
formed when radon undergoes radioactive decay.
None of the above.
_____ 102. Xenon oxides
A.
B.
C.
D.
E.
are unknown.
are more stable than the fluorides.
are formed by the direct reaction of xenon with oxygen.
are useful intermediates.
None of the above.
_____ 103. The molecular geometry of XeF6 is best described as
A.
B.
C.
D.
E.
tetrahedral.
octahedral.
square pyramidal.
trigonal bipyramidal.
None of the above.
_____ 104. Other than radon, the noble gases
A.
B.
C.
D.
E.
are toxic to humans.
are beneficial to humans.
require special precautions to protect the environment.
are deposited in human bones.
None of the above.
_____ 105. Which element has no radioactive isotopes?
A.
B.
C.
D.
E.
uranium.
potassium.
hydrogen.
carbon.
None of the above.
_____ 106. Which of the following sets only contains "magic numbers?"
A.
B.
C.
D.
E.
8, 24, 26, 52, 82, and 124.
8, 20, 30, 50, 80, and 128.
8, 20, 28, 50, 82, and 126.
2, 20, 26, 54, 82, and 126.
None of the above.
_____ 107. The greater the mass defect
A.
B.
C.
D.
E.
the more stable the nucleus.
the more radioactive the nucleus.
the smaller the nucleus.
the more unstable the nucleus.
None of the above.
_____ 108. An isotope with too many protons will most likely undergo
A.
B.
C.
D.
E.
electron capture or positron emission.
electron capture.
positron emission.
proton emission.
None of the above.
_____ 109. An isotope with
A.
B.
C.
D.
E.
an even number of protons and an odd number of neutrons is likely to be unstable.
an odd number of protons and an odd number of neutrons is likely to be unstable.
an odd number of protons and an even number of neutrons is likely to be unstable.
more neutrons than electrons.
None of the above.
_____ 110. The radioactive decay series are the
A.
B.
C.
D.
E.
thorium, neptunium, and uranium series.
neptunium, uranium, and actinium series.
thorium, uranium, and actinium series.
thorium, neptunium, and actinium series.
None of the above.
_____ 111. The first artificially produced radioisotope was
A.
B.
C.
D.
E.
nitrogen-13.
technetium-99.
radium-226.
radon-222.
None of the above.
_____ 112. The first attempt to synthesize a transuranium element was by
A.
B.
C.
D.
E.
Fermi.
Rutherford.
Curie.
Einstein.
None of the above.
_____ 113. Breeder reactors
A.
B.
C.
D.
E.
produce more fissionable material than they consume.
produce more fusionable material than they consume.
provide a safer means of generating nuclear energy.
provide most of the uranium-235.
None of the above.
_____ 114. Fusion requires
A.
B.
C.
D.
E.
very low temperatures.
very high temperatures.
very low pressures.
a supply of neutrons.
None of the above.
_____ 115. The slow step in the initiation of the product of stellar energy is
A.
B.
C.
D.
E.
the formation of helium-3.
the formation of hydrogen-3.
the formation of helium-4.
the formation of hydrogen-2.
None of the above.
_____ 116. The second most abundant element in the Universe is
A.
B.
C.
D.
E.
hydrogen.
silicon.
iron.
oxygen.
None of the above.
_____ 117. The elements that are particularly rare in the Universe are
A.
B.
C.
D.
E.
lithium, beryllium, and carbon.
beryllium, boron, and carbon.
beryllium, boron, and nitrogen.
boron, nitrogen and fluorine.
None of the above.
_____ 118. The Helium Problem arises
A.
B.
C.
D.
E.
because there is too much helium present in the Universe.
because helium is too stable to react.
because there is no way to form helium.
because there is too little helium present in the Universe.
None of the above.
_____ 119. Helium burning in stars may produce nuclei up to
A.
B.
C.
D.
E.
iron-56.
carbon-12.
beryllium-8.
neon-20.
None of the above.
_____ 120. The limit of slow neutron capture in the genesis of the elements is
A.
B.
C.
D.
E.
uranium-238.
bismuth-209.
iron-56.
uranium-235.
None of the above.
_____ 121. Rapid neutron capture may produce elements up to
A.
B.
C.
D.
E.
lead and bismuth.
thorium and uranium.
iron and cobalt.
radon and radium.
None of the above.
_____ 122. The p-process is responsible for
A.
B.
C.
D.
E.
proton-rich nuclei of low abundance.
nuclei that undergo proton emission.
proton-rich nuclei of high abundance.
deuterium.
None of the above.
_____ 123. A nova or supernova explosion could produce elements up to at least
A.
B.
C.
D.
E.
element 100.
element 114.
element 298.
element 112.
None of the above.
_____ 124. A star with a mass between 1.4 and 3 times the mass of the Sun will
A.
B.
C.
D.
E.
become a white dwarf.
become a nova.
become a supernova.
not burn out.
None of the above.
_____ 125. The minimum mass necessary to produce a black hole is
A.
B.
C.
D.
E.
1.4 times the mass of the Sun.
10 times the mass of the Sun.
3 times the mass of the Sun.
5 times the mass of the Sun.
None of the above.