Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Change of State
56 practice questions
Topics covered
Practice questions
21–30 of 31 · Normal
Question 21
4 marks · Normal
Answer and see the solution →A student heats a sample of solid wax in a beaker and records the temperature every minute as it melts and becomes a liquid.
(a)[2 marks]Describe what happens to the temperature of the wax just as it is melting, even though heating continues.
(b)[2 marks]Explain why the temperature behaves this way during melting.
Question 22
3 marks · Normal
Answer and see the solution →An electric heater supplies 200 W to a block of ice at -10°C. The ice has a mass of 0.5 kg. The specific heat capacity of ice is 2100 J/kg°C. Calculate the time needed to raise the temperature of the ice to 0°C.
Question 23
4 marks · Normal
Answer and see the solution →You are asked to investigate the melting of naphthalene in the laboratory.
(a)[2 marks]List two pieces of equipment you need to measure the temperature at fixed time intervals as naphthalene melts.
(b)[2 marks]Explain one safety precaution you should take when carrying out this investigation.
Question 24
3 marks · Normal
Answer and see the solution →Explain, in terms of particles, what happens to the thermal energy and movement of particles in a pure substance as it melts at its melting point.
Question 25
4 marks · Normal
Answer and see the solution →A group of students heated a small sample of solid naphthalene. They recorded the temperature every minute for 15 minutes. The melting point of naphthalene is 80°C. Their results are shown below.
Temperature readings for naphthalene Time (min) Temperature (°C) 0 40 2 55 4 69 6 80 8 80 10 80 12 86 15 93 Use the table to answer the questions.
(a)[1 mark]For how many minutes did the naphthalene remain at 80°C?
(b)[2 marks]Explain why the temperature stayed at 80°C for this time even though the substance was being heated.
(c)[1 mark]What was happening to the naphthalene during this period?
Question 26
1 mark · Normal
Answer and check →Which statement best describes the change in energy as a substance boils at its boiling point?
- A.The substance's temperature keeps increasing as it boils.
- B.The supplied energy is used to break the bonds between particles.
- C.The energy supplied is lost to the surroundings.
- D.The energy is used to increase the mass of the liquid.
Question 27
3 marks · Normal
Answer and see the solution →A mixture of ice and water is kept at 0°C. Explain, using ideas about energy and particles, what happens to the temperature when more ice melts.
Question 28
6 marks · Normal
Answer and see the solution →A student carries out an experiment to find the specific heat capacity of water. The following results are obtained:
Experimental Data Mass of water (kg) Initial temp (°C) Final temp (°C) Current (A) Voltage (V) Time (s) 0.80 20 60 2.0 12 300 (a)[2 marks]Calculate the total energy supplied by the heater (in J).
(b)[3 marks]Use the data to calculate the specific heat capacity of water based on this experiment.
(c)[1 mark]Suggest one reason why the value found might be higher than the actual specific heat capacity of water.
Question 29
6 marks · Normal
Answer and see the solution →A student heats a beaker of ice at -10 °C. The temperature is measured every minute and the following readings are recorded:
Temperature of Ice/Water Over Time Time (min) Temperature (°C) 0 -10 2 -5 4 0 8 0 10 10 (a)[3 marks]Describe the changes in the state of the substance over the 10 minutes.
(b)[2 marks]Explain why the temperature remains at 0 °C from 4 to 8 minutes, even though energy is still being supplied.
(c)[1 mark]Using the particle model, describe what happens to the arrangement and movement of particles during this period.
Question 30
7 marks · Normal
Answer and see the solution →A student uses an electric heater to warm a metal block from room temperature. The temperature of the block is recorded every minute. After some time, the block begins to melt.
(a)[3 marks]Describe how the arrangement and motion of the particles in the block change as it is heated and melts.
(b)[3 marks]When the temperature is rising, the student records a temperature change of 24 °C for a 0.4 kg block. The heater supplies 8400 J of energy during this time. Calculate the specific heat capacity (c) of the metal.
(c)[1 mark]Explain why the temperature remains constant while the block is melting, even though the heater is still supplying energy.