Particle ModelEdexcel GCSE Physics: Topic test

20 questions, 54 marks

Edexcel GCSE Physics

Particle Model topic test

Total 54 marks

Name

Class

Date

1
A jeweller wants to check whether a bar of metal is genuine gold. She measures the bar's mass using a digital balance, then finds its volume by lowering it into a measuring cylinder partly filled with water and recording the rise in water level. She then calculates the bar's density and compares it with the known density of pure gold, 19 300 kg/m³.
(a)
Why does lowering the metal bar into the measuring cylinder allow the jeweller to find its volume?
[1 mark]
AThe metal bar dissolves slightly in the water, changing its mass
BThe bar pushes aside (displaces) a volume of water exactly equal to its own volume
CThe water cools the bar down, which shrinks its volume to a known reference value
DThe rise in water level shows how much the bar's mass has increased
(b)
The jeweller measures the bar's mass as 0.579 kg and finds that the water level rises by 30 cm³ (0.00003 m³). What is the bar's density, and does this suggest the bar is genuine gold?
[1 mark]
A19 300 kg/m³ — this matches pure gold, so the bar is genuine
B9 650 kg/m³ — this is below pure gold's density, so the bar might not be genuine
C579 000 kg/m³ — this is far above gold's density
D0.0000193 kg/m³ — an implausibly small result
(c)
Explain why measuring volume by water displacement is a suitable method for this metal bar, and describe one source of error that could make the calculated density less accurate.
[2 marks]
Total for question 1: 4 marks
2
A weather balloon is released from the ground carrying a package of instruments. At ground level, the balloon contains 4.0 m³ of helium gas at a pressure of 100 kPa. As the balloon rises through the atmosphere, the external air pressure around it falls, and the balloon expands. Throughout the ascent, the temperature of the gas inside the balloon can be assumed to stay approximately constant.
(a)
Which equation should be used to calculate the balloon's new volume once the external pressure has fallen, given that the temperature of the gas stays approximately constant?
[1 mark]
AQ = m × L
Bρ = m/V
CP1V1 = P2V2
DP = F/A
(b)
By the time the balloon has risen to an altitude where the external pressure has fallen to 40 kPa, what is the new volume of the gas inside it?
[1 mark]
A10 m³
B1.6 m³
C40 m³
D0.4 m³
(c)
Explain, in terms of the motion of gas particles, why reducing the external pressure on the balloon while its temperature stays constant results in it occupying a larger volume.
[2 marks]
Total for question 2: 4 marks
3
An ice sculpture with a mass of 4.5 kg is left outside at exactly 0°C, its melting point, on a warm day. All of the thermal energy transferred to the ice goes into melting it rather than raising its temperature. The specific latent heat of fusion of ice is 334 000 J/kg.
(a)
Calculate the thermal energy needed to completely melt the ice sculpture.
[3 marks]
(b)
Explain, in terms of particles, why the temperature of the ice does not rise above 0°C while it is melting, even though thermal energy is still being transferred to it continuously.
[4 marks]
Total for question 3: 7 marks
4
A hot air balloon rises by heating the air inside its envelope using a gas burner. The envelope has an opening at the bottom, so the heated air inside is free to expand and is always at approximately the same pressure as the surrounding atmosphere. As the burner heats the air, some of it escapes out of the opening at the bottom, so the mass of air remaining inside the envelope decreases as its temperature rises.
(a)
Explain, in terms of particle motion and spacing, why heating the air inside the envelope and allowing some of it to escape causes the density of the air remaining inside to fall, and explain how this makes the balloon rise.
[6 marks]
(b)
Explain, using the idea that gas pressure is caused by particle collisions with a surface, why the pressure of the air inside the envelope stays approximately equal to the pressure of the air outside, even though its temperature is much higher.
[6 marks]
Total for question 4: 12 marks
5
A school weather station records the outdoor air temperature every hour in degrees Celsius, but the students' physics coursework requires all gas calculations to use the kelvin scale. One reading taken overnight was −18 °C.
(a)
Convert the overnight temperature reading of −18 °C to kelvin.
[1 mark]
A291 K
B−291 K
C18 K
D255 K
(b)
What is true of the particles of a substance at a temperature of exactly 0 K (absolute zero)?
[1 mark]
AThey are moving at their fastest possible speed
BThey have, in theory, no kinetic energy and are not moving
CThey have turned into a plasma and are highly energetic
DThey vibrate more violently than at any higher temperature
(c)
Explain why temperatures on the kelvin scale can never be negative, referring to the motion of particles.
[2 marks]
Total for question 5: 4 marks
6
A stage crew uses blocks of solid carbon dioxide, known as dry ice, to create a fog effect at a concert. When a 2.0 kg block of dry ice is placed in a container of warm water, it sublimates directly into carbon dioxide gas, which sinks and spreads across the stage floor as a visible white fog, without ever appearing to turn into a liquid.
(a)
What name is given to the change of state in which the solid dry ice turns directly into carbon dioxide gas, without becoming a liquid?
[1 mark]
AEvaporation
BCondensation
CSublimation
DDeposition
(b)
Once the whole 2.0 kg block of dry ice has sublimated completely into carbon dioxide gas, what is the total mass of carbon dioxide gas produced?
[1 mark]
ALess than 2.0 kg, because some mass is lost as visible fog
BMore than 2.0 kg, because the gas absorbs water from the air
CZero, because the gas disperses and no longer has a measurable mass
DExactly 2.0 kg, because mass is conserved during a change of state
(c)
Explain why the fog appears to sink and spread across the stage floor rather than rising into the air.
[2 marks]
Total for question 6: 4 marks
7
A scuba diving cylinder has an internal volume of 12 litres. Before a dive, a compressor fills the cylinder with air. At the surface, before filling, the air inside the empty cylinder is at atmospheric pressure, 100 kPa, occupying the full 12 litre volume. The compressor then forces more air into the same rigid 12 litre cylinder until the pressure inside reaches 20 000 kPa, assuming the temperature stays constant during filling.
(a)
Using P1V1 = P2V2, calculate the volume that the compressed air inside the full cylinder would occupy if it were released and allowed to expand back to atmospheric pressure of 100 kPa, at the same temperature.
[3 marks]
(b)
Explain, in terms of the motion and collisions of gas particles, why forcing more air into the same rigid volume increases the pressure inside the cylinder.
[4 marks]
Total for question 7: 7 marks
8
A pressure cooker is a sealed pot used to cook food faster. Water is heated inside the sealed pot; as it heats, some of the liquid water evaporates into steam, and because the lid is sealed, the steam produced is trapped inside a fixed volume. The build-up of pressure inside allows the water to reach a boiling point above the normal 100 °C it would have at atmospheric pressure, cooking the food more quickly.
(a)
Explain, in terms of the specific heat capacity and specific latent heat of water, why heating the water inside the pressure cooker to its boiling point and then evaporating some of it requires two separate stages of energy transfer.
[6 marks]
(b)
Explain, using the particle model of a gas, why trapping the steam produced in a sealed, fixed volume causes the pressure inside the pressure cooker to build up, and explain why this rise in pressure allows the water to boil at a temperature above 100 °C.
[6 marks]
Total for question 8: 12 marks

End of questions