AP Chemistry Final Exam with Verified
Answers
A student has samples of two pure compounds, XClO3 and ZClO3, which contain unknown alkali
metals X and Z. The student measures the mass of each sample and then strongly heats the
samples to drive off all the oxygen, leaving solid residues of XCl and ZCl. The student measures
the mass of the solid residue from each sample. Which of the following questions can be
answered from the results of the experiment? A) Which has the great molar mass, X or Z? B)
Which has the higher boiling point, X or Z? C) Which has the higher melting point, XCl or ZCl? D)
Which has the greater density, XCL or ZCl? - ✔✔A
Which of the following ground-state configurations represents the atom that has the lowest
first-ionization energy? A) 1s2,2s1 B) 1s2,2s2,2p2 C) 1s2,2s2,2p6 D) 1s2,2s2,2p6,3s1 - ✔✔D
Use the electron configuration below to identify the element and then determine the formula if
it bonds with K: 1s2, 2s2, 2p6, 3s2, 3p4 - ✔✔K2S
Which of the following best helps to explain why the electron affinity of Br has a greater
magnitude than that of I? A) Br has a lower electronegativity than I, B) Br has a lower ionization
energy than I, C) An added electron would go into a new shell in Br but not I, D) there is a
greater attraction between an added electron and the nucleus in Br than I - ✔✔D
Which of the following represents an electron configuration that corresponds to the valence
electrons of an element for which there is an especially large jump between the second and
third ionization energies? (Note: n represents a principal quantum number equal to or greater
than 2.) A) ns2, B) ns2,np1, C) ns2, np2, D) ns2,np3 - ✔✔A
RbCl has a high boiling point. Which of the following compounds is also likely to have a high
boiling point and why? A) NO because its elements are in the same period of the periodic table,
B) ClF because its elements are in the same group of the periodic table, C) Cl2O because its
elements have similar electronegativities and it is a covalent compound, D) CsCl because its
elements have very different electronegativities and it is an ionic compound - ✔✔D
,A student claims that He has a higher electronegativity than F. Do you agree and justify? - ✔✔I
do not agree, He is a noble gas therefore it doesn't have electronegativity since it's already
stable.
Since hydrogen is the lightest element in the universe, a student argues that it must also have
the smallest atomic radius. Do you agree and justify your answer? - ✔✔I do not agree, He has
the same shell, but it has one more proton and electron, so the pull between them and the
nucleus is greater than hydrogens causing it's radius to be smaller.
A student obtains a 10.0g sample of a white powder labeled as BaCl2. After completely
dissolving the powder in 50.0mL of distilled water, the student adds excess Na2SO4(s), which
causes a precipitate of BaSO4(s) to form, as represented by the equation above. The student
filters the BaSO4(s), rinses it, and dries it until its mass is constant. Which of the following
scientific questions could best be answered based on the results of the experiment?
Responses
A) Is the Na2SO4(s) used in the experiment pure? B) Is the BaCl2(s) used in the experiment
pure? C) What is the molar solubility of BaCl2 in water? D) What is the molar solubility of BaSO4
in water? - ✔✔B
A student measures the mass of a sample of a metallic element, M. Then the student heats the
sample in air, where it completely reacts to form the compound MO. The student measures the
mass of the compound that was formed. Which of the following questions can be answered
from the results of the experiment? A) What is the density of M? B) What is the molar mass of
M?
C) What is the melting point of M? D) What is the melting point of MO? - ✔✔B
A 42.0g sample of compound containing only C and H was analyzed. The results showed that
the sample contained 36.0g of C and 6.0g of H. Which of the following questions about the
compound can be answered using the results of the analysis? A) What was the volume of the
sample? B) What is the molar mass of the compound? C) What is the chemical stability of the
compound? D) What is the empirical formula of the compound? - ✔✔D
, A student obtains a mixture of the chlorides of two unknown metals, X and Z. The percent by
mass of X and the percent by mass of Z in the mixture is known. Which of the following
additional information is most helpful in calculating the mole percent of XCl(s) and of ZCl(s) in
the mixture?
A) The number of isotopes of Cl B) The molar masses of X and Z C) The density of either XCl(s) or
ZCl(s) D) The percent by mass of Cl in the mixture - ✔✔B
A vessel contains a mixture of gases. The mass of each gas used to make the mixture is known.
Which of the following information is needed to determine the mole fraction of each gas in the
mixture? A) The molar mass of each gas
B) The density of the gases in the vessel C) The total pressure of the gases in the vessel D) The
number of atoms per molecule for each gas - ✔✔A
1s2, 2s2, 2p6, 3s2, 3p6, How many unpaired electrons are in the atom represented by the
electron configuration above? A) 0 B) 1 C) 2 D) 3 - ✔✔A
Which of the following is the correct electron configuration for a ground-state atom of
magnesium (atomic number 12)? A) 1s2,2s2,2p8 B) 1s2, 2s2, 3s2, 3p6 C) 1s2, 2s2, 2p6, 3s2 D)
1s2, 2s2, 3s4, 3p4 - ✔✔C
The atomic radii of the elements in the nitrogen group in the periodic table are given in the
table above. Which of the following best helps explain the trend of increasing atomic radius
from N to Bi? A) The number of particles in the nucleus of the atom increases. B) The number of
electrons in the outermost shell of the atom increases. C) The attractive force between the
valence electrons and the nuclei of the atoms decreases. D) The repulsive force between the
valence electrons and the electrons in the inner shells decreases. - ✔✔C
Which of the following best helps to explain why the atomic radius of K is greater than that of
Br? A) The first ionization energy of K is higher than that of Br. B) The valence electrons in K are
in a higher principal energy level than those of Br. C) In the ground state, an atom of K has
fewer unpaired electrons than an atom of Br has. D) The effective nuclear charge experienced
by valence electrons is smaller for K than for Br. - ✔✔D
Answers
A student has samples of two pure compounds, XClO3 and ZClO3, which contain unknown alkali
metals X and Z. The student measures the mass of each sample and then strongly heats the
samples to drive off all the oxygen, leaving solid residues of XCl and ZCl. The student measures
the mass of the solid residue from each sample. Which of the following questions can be
answered from the results of the experiment? A) Which has the great molar mass, X or Z? B)
Which has the higher boiling point, X or Z? C) Which has the higher melting point, XCl or ZCl? D)
Which has the greater density, XCL or ZCl? - ✔✔A
Which of the following ground-state configurations represents the atom that has the lowest
first-ionization energy? A) 1s2,2s1 B) 1s2,2s2,2p2 C) 1s2,2s2,2p6 D) 1s2,2s2,2p6,3s1 - ✔✔D
Use the electron configuration below to identify the element and then determine the formula if
it bonds with K: 1s2, 2s2, 2p6, 3s2, 3p4 - ✔✔K2S
Which of the following best helps to explain why the electron affinity of Br has a greater
magnitude than that of I? A) Br has a lower electronegativity than I, B) Br has a lower ionization
energy than I, C) An added electron would go into a new shell in Br but not I, D) there is a
greater attraction between an added electron and the nucleus in Br than I - ✔✔D
Which of the following represents an electron configuration that corresponds to the valence
electrons of an element for which there is an especially large jump between the second and
third ionization energies? (Note: n represents a principal quantum number equal to or greater
than 2.) A) ns2, B) ns2,np1, C) ns2, np2, D) ns2,np3 - ✔✔A
RbCl has a high boiling point. Which of the following compounds is also likely to have a high
boiling point and why? A) NO because its elements are in the same period of the periodic table,
B) ClF because its elements are in the same group of the periodic table, C) Cl2O because its
elements have similar electronegativities and it is a covalent compound, D) CsCl because its
elements have very different electronegativities and it is an ionic compound - ✔✔D
,A student claims that He has a higher electronegativity than F. Do you agree and justify? - ✔✔I
do not agree, He is a noble gas therefore it doesn't have electronegativity since it's already
stable.
Since hydrogen is the lightest element in the universe, a student argues that it must also have
the smallest atomic radius. Do you agree and justify your answer? - ✔✔I do not agree, He has
the same shell, but it has one more proton and electron, so the pull between them and the
nucleus is greater than hydrogens causing it's radius to be smaller.
A student obtains a 10.0g sample of a white powder labeled as BaCl2. After completely
dissolving the powder in 50.0mL of distilled water, the student adds excess Na2SO4(s), which
causes a precipitate of BaSO4(s) to form, as represented by the equation above. The student
filters the BaSO4(s), rinses it, and dries it until its mass is constant. Which of the following
scientific questions could best be answered based on the results of the experiment?
Responses
A) Is the Na2SO4(s) used in the experiment pure? B) Is the BaCl2(s) used in the experiment
pure? C) What is the molar solubility of BaCl2 in water? D) What is the molar solubility of BaSO4
in water? - ✔✔B
A student measures the mass of a sample of a metallic element, M. Then the student heats the
sample in air, where it completely reacts to form the compound MO. The student measures the
mass of the compound that was formed. Which of the following questions can be answered
from the results of the experiment? A) What is the density of M? B) What is the molar mass of
M?
C) What is the melting point of M? D) What is the melting point of MO? - ✔✔B
A 42.0g sample of compound containing only C and H was analyzed. The results showed that
the sample contained 36.0g of C and 6.0g of H. Which of the following questions about the
compound can be answered using the results of the analysis? A) What was the volume of the
sample? B) What is the molar mass of the compound? C) What is the chemical stability of the
compound? D) What is the empirical formula of the compound? - ✔✔D
, A student obtains a mixture of the chlorides of two unknown metals, X and Z. The percent by
mass of X and the percent by mass of Z in the mixture is known. Which of the following
additional information is most helpful in calculating the mole percent of XCl(s) and of ZCl(s) in
the mixture?
A) The number of isotopes of Cl B) The molar masses of X and Z C) The density of either XCl(s) or
ZCl(s) D) The percent by mass of Cl in the mixture - ✔✔B
A vessel contains a mixture of gases. The mass of each gas used to make the mixture is known.
Which of the following information is needed to determine the mole fraction of each gas in the
mixture? A) The molar mass of each gas
B) The density of the gases in the vessel C) The total pressure of the gases in the vessel D) The
number of atoms per molecule for each gas - ✔✔A
1s2, 2s2, 2p6, 3s2, 3p6, How many unpaired electrons are in the atom represented by the
electron configuration above? A) 0 B) 1 C) 2 D) 3 - ✔✔A
Which of the following is the correct electron configuration for a ground-state atom of
magnesium (atomic number 12)? A) 1s2,2s2,2p8 B) 1s2, 2s2, 3s2, 3p6 C) 1s2, 2s2, 2p6, 3s2 D)
1s2, 2s2, 3s4, 3p4 - ✔✔C
The atomic radii of the elements in the nitrogen group in the periodic table are given in the
table above. Which of the following best helps explain the trend of increasing atomic radius
from N to Bi? A) The number of particles in the nucleus of the atom increases. B) The number of
electrons in the outermost shell of the atom increases. C) The attractive force between the
valence electrons and the nuclei of the atoms decreases. D) The repulsive force between the
valence electrons and the electrons in the inner shells decreases. - ✔✔C
Which of the following best helps to explain why the atomic radius of K is greater than that of
Br? A) The first ionization energy of K is higher than that of Br. B) The valence electrons in K are
in a higher principal energy level than those of Br. C) In the ground state, an atom of K has
fewer unpaired electrons than an atom of Br has. D) The effective nuclear charge experienced
by valence electrons is smaller for K than for Br. - ✔✔D
