1. 1
   A carpenter has a block of wood with a mass of 0.6 kg and a volume of 0.001 m³, and wants to know whether it will float when placed in a bucket of water of density 1000 kg/m³.

   (a)

   A block of wood has a mass of 0.6 kg and a volume of 0.001 m³. Which equation should be used to calculate its density?

   [1 mark]

   • Adensity = mass × volume
   • Bdensity = mass / volume
   • Cdensity = volume / mass
   • Ddensity = mass + volume

   (b)

   The block of wood has a density of 600 kg/m³. Compared with water (density 1000 kg/m³), what will happen when the block is placed in the bucket of water?

   [1 mark]

   • AIt will float, because it is less dense than water
   • BIt will sink, because it is less dense than water
   • CIt will float, because it is denser than water
   • DIt will sink, because it is denser than water

   (c)

   Calculate the density of the block of wood and state the unit.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A geologist collects two rock samples of exactly the same volume from a quarry. Sample X feels much heavier than Sample Y when held, and she wants to explain this difference using the particle model of matter.

   (a)

   A geologist compares two rock samples of the same volume. Sample X is much heavier than Sample Y. What does this tell her about the arrangement of particles in Sample X compared with Sample Y?

   [1 mark]

   • ASample X has fewer, more widely spaced particles
   • BSample X must be a gas and Sample Y must be a solid
   • CSample X and Sample Y must have identical particle arrangements
   • DSample X has more closely packed particles (or heavier particles) in the same volume

   (b)

   The geologist heats Sample Y until part of it melts. Using the particle model, what mainly happens to the arrangement of particles as the solid rock melts into a liquid?

   [1 mark]

   • AParticles become fixed in a rigid regular pattern
   • BParticles disappear entirely
   • CParticles move further apart and are able to move past one another
   • DParticles stop vibrating completely

   (c)

   Explain, using the particle model, why the density of Sample Y's material generally decreases slightly when it changes from a solid to a liquid, even though its mass stays the same.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A chef seals steam inside a strong sealed pan and observes it condense into liquid water as it cools, then uses this to explain to an apprentice why the pan's contents behave so differently as a gas compared with a liquid.

   (a)

   A chef fills a sealed pan with steam (a gas) and then cools it until the steam condenses completely into liquid water inside the sealed pan. Using the particle model, describe the difference in the arrangement and motion of particles between the steam and the liquid water.

   [3 marks]

   (b)

   The sealed pan contains exactly 0.5 kg of water in total, whether as steam or as condensed liquid. Explain why the mass of water inside the sealed pan stays exactly the same throughout the change of state, and explain what happens to the density of the water as it condenses from steam to liquid.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A materials scientist is designing a life jacket and must select a foam material with the right density, using the particle model of matter, to guarantee that it floats reliably in seawater even when compressed during use.

   (a)

   A materials scientist is designing a life jacket and must choose a foam material with the right density to ensure it floats reliably in seawater (density approximately 1025 kg/m³), even when compressed slightly during use. Explain, using the particle model of matter and the equation for density, how the arrangement of particles within a solid material determines its density, and why choosing a material with a sufficiently low density is essential for the life jacket to float.

   [6 marks]

   (b)

   A rival manufacturer proposes using a solid rubber block, with a much higher density than foam, inside the life jacket instead, arguing rubber is more durable. Evaluate whether this rubber block would be a suitable replacement for the foam, explaining your reasoning using the particle model and the concept of density.

   [6 marks]

   Total for question 4: 12 marks

End of questions