Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Ideal Gas Molecules
70 practice questions
Topics covered
Practice questions
61–70 of 70
Question 61
3 marks · Normal
Answer and see the solution →A physics classroom is at 18 °C. A scientist is cooling a gas sample to investigate pressure at lower temperatures.
(a)[1 mark]Convert the classroom temperature to kelvin.
(b)[1 mark]The gas is cooled to 5 °C. What is this temperature in kelvin?
(c)[1 mark]If the gas were cooled to 0 K, what would happen to the motion of the particles? Explain.
Question 62
2 marks · Normal
Answer and see the solution →Why must you convert temperatures to kelvin before using gas law equations?
Question 63
1 mark · Normal
Answer and see the solution →A student writes this formula for converting celsius to kelvin:
T_kelvin = T_celsius + 273Question 64
5 marks · Easy
Answer and see the solution →A scientist traps a fixed mass of gas in a syringe sealed with a cap. She gently heats the syringe by placing it in warm water while making sure the plunger does not move. The initial temperature of the gas is 25°C and its pressure is 105 kPa. After heating, the gas temperature reaches 45°C. Assume the volume of the gas does not change.
(a)[1 mark]State which gas law links the pressure and temperature of a fixed volume of gas.
(b)[3 marks]Calculate the new pressure of the gas when it has reached 45°C. Give your answer to two significant figures.
(c)[1 mark]Explain, in terms of the motion of particles, why the pressure increases when the gas is heated.
Question 65
4 marks · Easy
Answer and see the solution →A fixed mass of gas is kept at a constant temperature of 300 K. The initial volume of the gas is 2.0 dm³ at a pressure of 100 kPa. The gas is then compressed to a pressure of 250 kPa.
(a)[1 mark]Name the law that relates the pressure and volume of the gas in this situation.
(b)[2 marks]Calculate the new volume of the gas after compression. Give your answer to two significant figures.
(c)[1 mark]State the assumption made about the temperature in order for this law to apply.
Question 66
4 marks · Easy
Answer and see the solution →A gas cylinder contains a fixed mass of oxygen at a pressure of 300 kPa and a temperature of 27°C. The gas escapes until the pressure drops to 100 kPa. The temperature does not change throughout the process.
(a)[2 marks]Explain, in terms of the number of particles, why the pressure in the cylinder decreases when gas escapes.
(b)[2 marks]If the initial volume of the gas was 4.5 litres, calculate the final volume of the remaining gas in the cylinder, assuming all other conditions stay the same.
Question 67
5 marks · Normal
Answer and see the solution →A student places a glass bottle full of air with a tight lid in a refrigerator. The air inside was initially at room temperature (22 °C) and atmospheric pressure (100 kPa). After several hours, the bottle’s temperature has dropped to 4 °C.
(a)[2 marks]Explain, using the idea of gas particles, what happens to the pressure of the air in the bottle as it cools.
(b)[3 marks]Calculate the final pressure of the air in the bottle, in kPa. Give your answer to 2 significant figures. (You must use the Kelvin scale for temperature.)
Question 68
5 marks · Normal
Answer and see the solution →A fixed mass of gas in a metal cylinder is at a pressure of 120 kPa and a temperature of 300 K. The gas is then compressed while being heated, so that its temperature rises to 360 K and its volume halves.
(a)[1 mark]Write down the gas law equation that links pressure, volume, and temperature for a fixed mass of gas.
(b)[3 marks]Calculate the final pressure of the gas, in kPa.
(c)[1 mark]Explain why the pressure in the cylinder increases, even though the gas is heated.
Question 69
5 marks · Normal
Answer and see the solution →A balloon filled with helium has a pressure of 105 kPa and a volume of 1.8 litres at 25°C. The balloon is taken outside where the temperature drops to 5°C, but the pressure remains constant.
(a)[2 marks]Explain what happens to the average kinetic energy of the helium molecules as the temperature changes. Your answer should refer to the temperature in Kelvin.
(b)[3 marks]Calculate the new volume of the balloon at 5°C. Give your answer to 2 significant figures.
Question 70
5 marks · Normal
Answer and see the solution →The graph below shows how the pressure of a fixed mass of gas at constant volume varies with temperature:
Graph of pressure vs. temperature (°C) for a fixed volume of gas (a)[2 marks]Determine the temperature at which the pressure of the gas would reach zero according to the graph.
(b)[3 marks]Explain what this value represents physically, and how it is linked to the kinetic energy of the gas molecules.