Chem 120 A+ Questions and Answers
2024 100% Verified
Helium gas is being pumped into a rigid container at a constant temperature. As a
result, the pressure of helium in the container is increasing. Select the one correct
statement below.
-As the pressure increases, helium atoms stay closer to the wall of the container, on
average.
-As the pressure increases, there are more collisions of helium atoms with the container
wall.
-As the pressure increases, helium atoms move faster, on average. -As
the pressure increases, helium atoms move more slowly, on average.
-As the pressure increases, the volume of the container must decrease. - ANS-As the
pressure increases, there are more collisions of helium atoms with the container wall.
Which of the following statements are not true about the process of vaporisation:
-The boiling point of a liquid is the temperature at which the vapour pressure equals the
external temperature
-Some molecules have enough potential energy to overcome attractions and vapourise
-Strong intermolecular forces usually lead to high boilings points (at normal pressure)
-As the external pressure on a liquid increases, the boiling point increases - ANS-Some
molecules have enough potential energy to overcome attractions and vapourise
At the critical point of a phase diagram:
-The critical point is the same as the triple point
, -Separate liquid and gas phases cease to exist
-The gas phase ceases to exist
-The liquid phase ceases to exist - ANS-Separate liquid and gas phases cease to exist
Which of the following is not a consideration for determining the state of a substance at
room temperature and pressure?
-Strength of the intermolecular forces
-Molecular shape
-Molecular mass
-Crystal shape - ANS
Using the phase diagram (below), Determine the approximate temperature at which
graphite becomes vapour.
3500 K
4500 K
2500 K
1500 K - ANS-3500 K
A dipole is:
-An area of partial positive or negative charge on an atom or molecule -An area of
positive or negative charge on an ion caused by an externmal electrcial field -An area of
positive or negative charge on an ion
-An area of positive or negative charge on an atom or molecule - ANS-An area of partial
positive or negative charge on an atom or molecule
Assuming that the total energy of a system doesn't change, what is the impact of
increasing the temperature of a sample of gas in a fixed volume?
-The kinetic energy increases; the potential energy increases
-The kinetic energy decreases; the potential energy increases
-The kinetic energy increases; the potential energy decreases
-The kinetic energy decreases; the potential energy decreases - ANS-The kinetic
2024 100% Verified
Helium gas is being pumped into a rigid container at a constant temperature. As a
result, the pressure of helium in the container is increasing. Select the one correct
statement below.
-As the pressure increases, helium atoms stay closer to the wall of the container, on
average.
-As the pressure increases, there are more collisions of helium atoms with the container
wall.
-As the pressure increases, helium atoms move faster, on average. -As
the pressure increases, helium atoms move more slowly, on average.
-As the pressure increases, the volume of the container must decrease. - ANS-As the
pressure increases, there are more collisions of helium atoms with the container wall.
Which of the following statements are not true about the process of vaporisation:
-The boiling point of a liquid is the temperature at which the vapour pressure equals the
external temperature
-Some molecules have enough potential energy to overcome attractions and vapourise
-Strong intermolecular forces usually lead to high boilings points (at normal pressure)
-As the external pressure on a liquid increases, the boiling point increases - ANS-Some
molecules have enough potential energy to overcome attractions and vapourise
At the critical point of a phase diagram:
-The critical point is the same as the triple point
, -Separate liquid and gas phases cease to exist
-The gas phase ceases to exist
-The liquid phase ceases to exist - ANS-Separate liquid and gas phases cease to exist
Which of the following is not a consideration for determining the state of a substance at
room temperature and pressure?
-Strength of the intermolecular forces
-Molecular shape
-Molecular mass
-Crystal shape - ANS
Using the phase diagram (below), Determine the approximate temperature at which
graphite becomes vapour.
3500 K
4500 K
2500 K
1500 K - ANS-3500 K
A dipole is:
-An area of partial positive or negative charge on an atom or molecule -An area of
positive or negative charge on an ion caused by an externmal electrcial field -An area of
positive or negative charge on an ion
-An area of positive or negative charge on an atom or molecule - ANS-An area of partial
positive or negative charge on an atom or molecule
Assuming that the total energy of a system doesn't change, what is the impact of
increasing the temperature of a sample of gas in a fixed volume?
-The kinetic energy increases; the potential energy increases
-The kinetic energy decreases; the potential energy increases
-The kinetic energy increases; the potential energy decreases
-The kinetic energy decreases; the potential energy decreases - ANS-The kinetic
