1.
- Some ice cubes are taken from a deep-freeze and placed in a metal container. The container is heated at a constant rate and readings of temperature and time are taken. The results are recorded on a graph.
Which temperature corresponds to 0 °C?
Correct Answer
C. C
Explanation
Based on the information given, the ice cubes were taken from a deep-freeze, which means they were at a temperature of 0 °C. Therefore, the temperature that corresponds to 0 °C on the graph would be point C.
2.
The diagrams show a bimetallic strip when it is at room temperature and after ithas been cooled. The change in shape occurs because
Correct Answer
A. Brass contracts more than invar.
Explanation
When the bimetallic strip is cooled, both the brass and invar contract. However, brass contracts more than invar. This difference in contraction causes the bimetallic strip to bend or change shape.
3.
The energy required to change liquid water into water vapour at the sametemperature is called latent heat of vaporisation.What does this energy do?
Correct Answer
A. Increases the average speed of the water molecules
Explanation
The energy required to change liquid water into water vapor, known as latent heat of vaporization, increases the average speed of the water molecules. This energy is used to overcome the intermolecular forces holding the water molecules together, allowing them to break free and move more rapidly as vapor.
4.
A 2 kW kettle containing boiling water is placed on a balance. It is left there andcontinues 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 ofvaporisation of water?
Correct Answer
A. 3 000 000 J / kg
Explanation
When the kettle is placed on the balance and the water inside continues to boil, the balance reading changes by 0.2 kg. This change in mass is due to the water vaporizing into steam. The specific latent heat of vaporization is the amount of energy required to convert 1 kg of a substance from liquid to gas at a constant temperature and pressure. In this case, the change in mass is 0.2 kg, and the kettle has a power of 2 kW. Given that the boiling process takes 5 minutes, we can calculate the energy transferred using the formula: Energy = Power x Time. Therefore, the specific latent heat of vaporization of water is 3,000,000 J/kg.
5.
What is the definition of heat capacity?
Correct Answer
A. The quantity of heat required to raise the temperature of an object through 1 K
Explanation
Heat capacity is defined as the quantity of heat required to raise the temperature of an object through 1 K. This means that it measures the amount of heat energy needed to increase the temperature of an object by 1 degree Kelvin. It is a property that depends on the mass and material of the object, and it is commonly used to describe the ability of a substance or object to store and transfer heat.
6.
Fillings in teeth should be made from a material which
Correct Answer
A. Expands by the same amount as the tooth when heated.
Explanation
When a tooth is heated, it expands. Therefore, it is important for fillings in teeth to be made from a material that also expands by the same amount as the tooth when heated. If the filling material expands more than the tooth, it could cause pressure and damage to the tooth. If it expands less than the tooth, there may be gaps between the filling and the tooth, allowing bacteria to enter and cause decay. If the filling material does not expand at all when heated, it may not fit properly in the tooth and could become loose or fall out.
7.
The graph shows the cooling curve of a hot substance.
Correct Answer
A. B
8.
The diagram shows the design for an alarm.The mercury pellet moves and completes the circuit.Why does this happen? temperaturegasAfallscontractsBfallsexpandsCrisescontractsDrisesexpands
Correct Answer
D. D
Explanation
When the temperature rises, the gas inside the alarm expands. This causes the mercury pellet to move and complete the circuit, triggering the alarm.
9.
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?
Correct Answer
A. To allow for expansion of the rail sections during hot weather
Explanation
The reason for the gap between the rail sections is to allow for expansion of the rail sections during hot weather. When the temperature rises, the metal rails expand, and if there were no gaps, the rails would buckle or warp. By providing gaps between the rail sections, the rails can expand without causing any damage or obstruction to the train's movement.
10.
Using an electric kettle, 100 g of water at 100 °C is converted into steam at100 °C in 300 seconds. The specific latent heat of steam is 2250 J / g. What is the average electrical power used?
Correct Answer
B. B
Explanation
The average electrical power used can be calculated using the formula: Power = Energy / Time. In this case, the energy can be calculated by multiplying the specific latent heat of steam (2250 J/g) by the mass of water (100 g), which gives us 225,000 J. The time is given as 300 seconds. Therefore, the average electrical power used is 225,000 J / 300 s = 750 W.
11.
The table shows the increase in length of four metals when heated through the same temperature rise. Each metal initially has the same length.A bimetallic strip is made from two of the metals. When heated, it bends in the direction shown.
Correct Answer
A. A
Explanation
The bimetallic strip bends in the direction shown because metal A has a greater increase in length when heated compared to metal B. This causes one side of the strip to expand more than the other, resulting in the bending motion.
12.
When ice melts to become water, which force must be overcome?
Correct Answer
C. The force between molecules
Explanation
When ice melts to become water, the force that must be overcome is the force between molecules. In the solid state, the water molecules are held together by intermolecular forces, specifically hydrogen bonding. When heat is applied, the kinetic energy of the molecules increases, causing them to vibrate and break free from the rigid structure of the ice. This requires overcoming the force of attraction between the molecules, allowing them to move more freely and form a liquid.
13.
A substance that is originally a solid is heated strongly for some time. At one stage, the energy given to the substance is used as latent heat ofvaporisation.At this stage, what change does the energy cause?
Correct Answer
A. It breaks the bonds holding the molecules together. Molecules escape from the liquid.
Explanation
When a substance is heated strongly, the energy given to the substance causes the bonds holding the molecules together to break. This results in the molecules escaping from the liquid, causing a phase change from liquid to gas.
14.
What happens when a metal bar is heated?
Correct Answer
A. The distance between the molecules increases, making the bar longer.
Explanation
When a metal bar is heated, the molecules within the bar gain energy and start to move more rapidly. This increased movement causes the molecules to push against each other, resulting in an expansion of the bar. As a result, the distance between the molecules increases, making the bar longer.
15.
A block of metal has a mass of 2.0 kg. Its specific heat capacity is 800 J / (kg oC).The block is supplied with 2400 J of energy. What is the rise in temperature?
Correct Answer
C. 1.5 oC
Explanation
The rise in temperature can be calculated using the formula:
Rise in temperature = Energy supplied / (Mass * Specific heat capacity)
Plugging in the given values:
Rise in temperature = 2400 J / (2.0 kg * 800 J / (kg oC))
Rise in temperature = 2400 J / 1600 J / oC
Rise in temperature = 1.5 oC
16.
A quantity of gas is trapped in a container by a piston exerting a force F.The temperature of the gas is raised while F remains unchanged.Which statement is correct?
Correct Answer
A. The gas expands.
Explanation
When the temperature of a gas is raised, the average kinetic energy of its molecules increases. This increase in kinetic energy leads to an increase in the speed and movement of the gas molecules. As a result, the gas molecules collide with the walls of the container more frequently and with greater force. This increased collision force causes the gas to exert a greater pressure on the piston. In order to maintain the pressure equilibrium, the piston is pushed upwards, allowing the gas to expand and occupy a larger volume. Therefore, the correct statement is that the gas expands.
17.
An ice-cube has a mass of 7.50 g. The ice-cube is at 0 oC.Heat from the surroundings reaches the ice-cube at an average rate of 1.25 J / s.How long does it take for all of the ice to melt? (specific latent heat of fusion of ice = 333 J / g)
Correct Answer
A. 2000 s
Explanation
The specific latent heat of fusion of ice is given as 333 J/g. This means that it takes 333 J of heat energy to melt 1 gram of ice. The ice cube has a mass of 7.50 g, so it will require 333 J/g x 7.50 g = 2497.5 J of heat energy to melt completely.
The heat from the surroundings is reaching the ice cube at an average rate of 1.25 J/s. Therefore, it will take 2497.5 J / 1.25 J/s = 1998 s to melt all of the ice.
Since the question is asking for the time it takes for all of the ice to melt, the correct answer is 2000 s.
18.
A bimetallic strip made from brass and iron is used as a thermostat.When the strip is heated, the brass expands more than the iron. Which shape will the strip become?*white=brass grey =iron
Correct Answer
A. B
Explanation
When the bimetallic strip made from brass and iron is heated, the brass expands more than the iron. As a result, the brass side of the strip will expand more than the iron side, causing the strip to bend towards the iron side. This bending shape is represented by option B in the given choices.