AP Chemistry Unit 1 questions and answers
Graded A+
Which of the following numerical expressions gives the number of moles in 5.0g
of CaO?
A
5.0g×56g/mol
B
5.0g56g/mol
C
56g/mol5.0g
D
15.0g×156g/mol - ✅✅B
5.0g56g/mol
Dividing the mass of the sample by the molar mass of CaO gives the number of
moles of CaO in the sample.
In a lab a student is given a 21g sample of pure Cu metal. Which of the following
pieces of information is most useful for determining the number of Cu atoms in
the sample? Assume that the pressure and temperature in the lab are 1.0atm and
25°C.
A
The molar mass of Cu
B
The density of Cu at 25°C
,C
The volume of the Cu sample
D
The ratio of the two main isotopes found in pure Cu - ✅✅A
The molar mass of Cu
By dividing the mass of the sample by the molar mass of Cu, the number of moles
of Cu in the sample can be calculated. A simple multiplication of that number with
Avogadro's number will provide the desired information.
A 1.0mol sample of which of the following compounds has the greatest mass?
A
NO
B
NO2
C
N2O
D
N2O5 - ✅✅D
N2O5
The mass of 1.0mol of NO is less than the mass of 1.0mol of N2O5 because it has
fewer N and O atoms and thus a smaller molar mass.
, The figure presents a graph of a mass spectrum with five vertical lines. The
horizontal axis is labeled Atomic Mass, in a m u, and the numbers 88 through 98,
in increments of 2, are indicated. The vertical axis is labeled Percent Abundance,
and the numbers 0, 50, and 100 are indicated. The five vertical lines from left to
right are as follows. Note all values are approximate. The first line begins on the
horizontal axis at 90 a m u, and extends to 52 percent. The second line begins on
the horizontal axis at 91 a m u, and extends to 11 percent. The third line begins on
the horizontal axis at 92 a m u, and extends to 17 percent. The fourth line begins
on the horizontal axis at 94 a m u, and extends to 17 percent. The fifth line begins
on the horizontal axis at 96 a m u, and extends to 3 percent.
The mass spectrum for an unknown element is shown above. According to the
information in the spectrum, the atomic mass of th - ✅✅B
91amu
By estimation, the weighted average of the isotope masses would be closer to 91
than 90.
The figure presents a graph of a mass spectrum with six vertical lines. The
horizontal axis is labeled Atomic Mass, in a m u, and the numbers 152 through
162, in increments of 1, are indicated. The vertical axis is labeled Relative
Abundance, and no values are indicated. The six vertical lines from left to right are
as follows. Note all values are approximate. The first line begins on the horizontal
axis at 154 a m u, and extends a small way up the vertical axis. The second line
begins on the horizontal axis at 155 a m u, and extends halfway up the vertical
axis. The third line begins on the horizontal axis at 156 a m u, and extends slightly
more than halfway up the vertical axis. The fourth line begins on the horizontal
axis at 157 a m u, and extends halfway up the vertical axis, but slightly more than
the second line. The fifth line begins on the horizontal axis at 158 a m u, and
extends high up the vertical axis. - ✅✅B
Gd
Graded A+
Which of the following numerical expressions gives the number of moles in 5.0g
of CaO?
A
5.0g×56g/mol
B
5.0g56g/mol
C
56g/mol5.0g
D
15.0g×156g/mol - ✅✅B
5.0g56g/mol
Dividing the mass of the sample by the molar mass of CaO gives the number of
moles of CaO in the sample.
In a lab a student is given a 21g sample of pure Cu metal. Which of the following
pieces of information is most useful for determining the number of Cu atoms in
the sample? Assume that the pressure and temperature in the lab are 1.0atm and
25°C.
A
The molar mass of Cu
B
The density of Cu at 25°C
,C
The volume of the Cu sample
D
The ratio of the two main isotopes found in pure Cu - ✅✅A
The molar mass of Cu
By dividing the mass of the sample by the molar mass of Cu, the number of moles
of Cu in the sample can be calculated. A simple multiplication of that number with
Avogadro's number will provide the desired information.
A 1.0mol sample of which of the following compounds has the greatest mass?
A
NO
B
NO2
C
N2O
D
N2O5 - ✅✅D
N2O5
The mass of 1.0mol of NO is less than the mass of 1.0mol of N2O5 because it has
fewer N and O atoms and thus a smaller molar mass.
, The figure presents a graph of a mass spectrum with five vertical lines. The
horizontal axis is labeled Atomic Mass, in a m u, and the numbers 88 through 98,
in increments of 2, are indicated. The vertical axis is labeled Percent Abundance,
and the numbers 0, 50, and 100 are indicated. The five vertical lines from left to
right are as follows. Note all values are approximate. The first line begins on the
horizontal axis at 90 a m u, and extends to 52 percent. The second line begins on
the horizontal axis at 91 a m u, and extends to 11 percent. The third line begins on
the horizontal axis at 92 a m u, and extends to 17 percent. The fourth line begins
on the horizontal axis at 94 a m u, and extends to 17 percent. The fifth line begins
on the horizontal axis at 96 a m u, and extends to 3 percent.
The mass spectrum for an unknown element is shown above. According to the
information in the spectrum, the atomic mass of th - ✅✅B
91amu
By estimation, the weighted average of the isotope masses would be closer to 91
than 90.
The figure presents a graph of a mass spectrum with six vertical lines. The
horizontal axis is labeled Atomic Mass, in a m u, and the numbers 152 through
162, in increments of 1, are indicated. The vertical axis is labeled Relative
Abundance, and no values are indicated. The six vertical lines from left to right are
as follows. Note all values are approximate. The first line begins on the horizontal
axis at 154 a m u, and extends a small way up the vertical axis. The second line
begins on the horizontal axis at 155 a m u, and extends halfway up the vertical
axis. The third line begins on the horizontal axis at 156 a m u, and extends slightly
more than halfway up the vertical axis. The fourth line begins on the horizontal
axis at 157 a m u, and extends halfway up the vertical axis, but slightly more than
the second line. The fifth line begins on the horizontal axis at 158 a m u, and
extends high up the vertical axis. - ✅✅B
Gd
