WorksheetsU6 Revision for Mock 2024 - Thermal Physics
Total questions: 26
Worksheet time: 27mins
Why does an ideal gas exert pressure on its container?
The molecules of the gas collide continually with each other.
The molecules of the gas collide continually with the walls of the container.
The molecules of the gas collide inelastically with the walls of the container.
The weight of the molecules exerts a force on the walls of the container.
Which row best describes how the molecules move in solids, in liquids and in gases?
A
B
C
D
Which process does not require energy to be supplied?
boiling
evaporation
freezing
melting
Absolute zero is the temperature when
an ideal gas liquefies.
an object is in deep space.
atoms have no kinetic energy.
a white dwarf star ends its life.
A mixture of helium He2 and hydrogen H2 gases is maintained at a temperature of 300 K.
Which of the following is correct?
The average kinetic energy of the He2 molecules is greater than the average kinetic energy of the H2 molecules.
The average kinetic energy of the He2 molecules is the same as the average kinetic energy of the H2 molecules.
The average speed of the He2 molecules is greater than the average speed of the H2 molecules.
The average speed of the He2 molecules is the same as the average speed of the H2 molecules.
A container has an ideal gas. The mean square speed of the gas molecules in the container is 3.0 × 105 m2 s-2.
Over a period of time, a third of the gas molecules escape from the container. The pressure and volume of the gas in the container remain the same.
What is the mean square speed of the molecules left in the container?
1.0 × 105 m2 s-2
2.0 × 105 m2 s-2
4.5 × 105 m2 s-2
9.0 × 105 m2 s-2
The latent heat of vaporisation of a liquid is 2300 kJ kg-1 and it has a molar mass of 0.018 kg mol-1.
What is the energy required to change 30 moles of the liquid to gas?
4.1 × 104 J
1.2 × 106 J
6.9 × 107 J
3.8 × 109 J
Why does the pressure increase when a sealed container of gas is heated?
The gas molecules collide more often with each other.
The gas molecules expand when they are heated.
The gas molecules travel faster and hit the walls of the container more often.
There are more gas molecules present to collide with the walls of the container.
Two different sized boxes, P and Q, both contain the same number of nitrogen molecules. The molecules in box P have twice the root mean square speed of those in box Q. Which of the following must be correct?
The density of the gas in box P is greater than that in box Q.
The mean momentum of the molecules in box P is greater than those in box Q.
The pressure exerted by the gas in box P is greater than that in box Q.
The temperature of the gas in box P is greater than that in box Q.
Energy is supplied to a fixed mass of gas in a container. As a result, the mean squared speed of the gas molecules doubles.
The absolute temperature of the gas
remains constant
increases by a factor of
2increases by a factor of 2
increases by a factor of 4
An ideal gas is maintained at a constant temperature in a sealed container and the volume of the container is varied.
Which of the following is the correct statement about the pressure exerted by the gas?
The pressure is directly proportional to the volume.
The pressure is independent of the volume.
The pressure is inversely proportional to the volume.
The pressure is proportional to the square of the volume.
Samples of nitrogen gas and helium gas are at the same temperature. Compared with the helium molecules, the nitrogen molecules have
a lower mean square speed.
the same mean square speed.
a higher mean square speed.
a mean square speed dependent upon the amount of each gas.
A sealed gas jar contains a mixture of different gases. At a given temperature, the mean kinetic energy of the molecules of each gas
depends upon how much of each gas is present.
is greater for the gas with less massive molecules.
is greater for the gas with more massive molecules.
is the same for each gas in the mixture.
A sample of an ideal gas at 27 °C is placed in a sealed container. The gas is heated at constant volume to a temperature of 324 °C.
The ratio of the final pressure to the initial pressure exerted by the gas is approximately
1
2
4
12
When the absolute temperature of an ideal gas is doubled, the internal energy of the gas changes by a factor of
1
2
2
4
If hot liquid wax is left to cool, it will start to solidify at 45°C. The temperature of the wax will remain constant until all the wax has solidified.
Select the row in the table that correctly describes how molecular energy will change as the wax solidifies.
A
B
C
D
Which condition must apply for the work done by an expanding gas to be p∆V, where p is the pressure of the gas and ∆V is its change in volume?
No thermal energy must be supplied to the gas.
The expansion must be at a constant rate.
The pressure must be constant.
The temperature of the gas must be constant.
The average molecular kinetic energy of a sample of nitrogen gas is E. The gas is heated and its temperature changes from 200 K to 400 K.
Which of the following is the new average molecular kinetic energy?
E/4
E/2
2E
4E
The temperature of a room increases from 283 K to 293 K. The r.m.s. speed of the air molecules in the room increases by a factor of
1.02
1.04
1.41
2.00
What is the total internal energy of 2.4 mol of an ideal gas which has a temperature of 15 °C?
6.0 x 10-21 J
8.6 x 103 J
1.4 x 10-20 J
4.5 x 102 J
A data book contains the information in the diagram for ethanol.
Which of the following would be the correct way to calculate the mass of ethanol that condenses from the data given?
545 / 109,000
545 / 838,000
109,000 / 545
838,000 / 545
A cylinder contains a mixture of argon gas and neon gas. Argon molecules are twice as massive as neon molecules.
The value of the ratio mean square speed of argon molecules/mean square speed of neon molecules would be given by:
4
2
0.5
0.25
In the equation for the kinetic theory of an ideal gas, what does the expression
c2 represent?the mean speed of the molecules.
the mean speed of the molecules squared.
the mean square speed of the molecules.
the mean velocity of the molecules.
A sample of an ideal gas has pressure p, volume V and absolute temperature T.
The volume of the gas is decreased to 2/3 V and the temperature increased to 6/5 T.
Which of the following is the new pressure of the gas?
5/9 p
4/5 p
5/4 p
9/5 p
A metal block of mass 0.28 kg has an initial temperature of 82°C. It is then dropped into some cold water. The temperature of the block after 1.2 minutes is 20°C.
The specific heat capacity of the metal is 130 J kg-1 K-1.
What is the average thermal power transferred away from the metal block?
31 W
41 W
1900 W
2700 W
In the diagram the dashed line X shows the variation of pressure, p, with absolute temperature, T, for 1 mol of an ideal gas in a container of fixed volume.
Which line, A, B, C or D shows the variation for 2 mol of the gas in the same container?
A
B
C
D
