The graph shows the distribution of speeds for the molecules of a gas at a particular temperature.
Which statement is correct?
A All the molecules have the same kinetic energy.
B The commonest value of speed is also the average speed.
C The graph shows that the molecules of a gas are widely spaced apart.
D The peak value of the graph would move to the right if the temperature is increased.
A gas is enclosed inside a cylinder which is fitted with a frictionless piston.
Initially, the gas has a volume V1 and is in equilibrium with an external pressure p. The gas is then heated slowly so that it expands, pushing the piston back until the volume of the gas has increased to V2.
How much work is done by the gas during this expansion?
A p(V2 –V1)
B 1/2.p(V2 –V1)
C p(V2 +V1)
D 1/2.p(V2 +V1)
If the Universe was such that the speed of the molecules in a substance increased with temperature but at any particular temperature the speed of all the molecules in a substance was the same, which process would not occur?
Which process does not require energy to be supplied?
A gas is enclosed in a container of fixed volume. It gains heat energy from an external source.
What happens to the molecules of the gas?
A They expand.
B They move faster inside the container.
C They move further apart.
D They vibrate with greater frequency.
A hot liquid is allowed to cool. The graph shows the cooling curve.
In which part of the curve is latent heat released?
The molar mass of magnesium is 24 g. 12 g of magnesium contains the same number of particles as:
A. 6 g of carbon-12.
B. 12 g of carbon-12.
C. 24 g of carbon-12.
D. 6.02 × 10^23 g of carbon-12.
A fixed mass of an ideal gas is at temperature T. The pressure is doubled and the volume is halved.
What is the temperature after these changes?
Ice at –10 °C is heated at a constant rate until it is water at +10 °C.
Which graph shows how the temperature changes with time?
Which of the following is NOT an ideal gas assumption?
A Molecules move with a range of speeds
B The volume of the molecules is negligible compared with the volume of the gas itself
C Molecules exert forces on each other even when not in contact
D The collisions of the molecules with each other and the container walls are elastic.
At regular intervals along a railway line there is a gap between the rail sections.
What is the reason for the gap between the rail sections?
A to allow for expansion of the rail sections during hot weather
B to allow for vibrations of the rail sections as the train passes over them
C to allow rain water to drain from the rail sections
D to keep the wheels of the train and carriages on the rail sections
Ice is taken from a freezer and left in a room. The ice melts and eventually the water reaches room temperature.
Which energy transfers take place?
Some air is trapped inside a small balloon. The average kinetic energy of the air molecules in the balloon is increased.
What remains the same?
A the density of the air in the balloon
B the mass of the air in the balloon
C the temperature of the air in the balloon
D the volume of the air in the balloon
A clinical thermometer is designed to respond quickly to a change in temperature and to have a high sensitivity.
Which design features should the clinical thermometer have?
A Bulb: thick glass; Bore: narrow
B Bulb: thick glass; Bore: wide
C Bulb: thin glass; Bore: narrow
D Bulb: thin glass; Bore: wide
The energy required to change liquid water into water vapour at the same temperature is called latent heat of vaporisation.
What does this energy do?
A increases the average separation of the water molecules
B increases the average speed of the water molecules
C raises the temperature of the air near the water
D splits the water molecules into their separate atoms
A 2 kW kettle containing boiling water is placed on a balance. It is left there and continues to boil for 5 minutes. The balance reading changes by 0.2 kg.
What does this information give as a value for the specific latent heat of vaporisation of water?
A 2000 J / kg
B 3000 J / kg
C 50 000 J / kg
D 3 000 000 J / kg