1. 1
   A jeweller weighs a small gold ring and finds its mass to be 38.6 g. By lowering the ring into a measuring cylinder of water, the jeweller finds its volume to be 2.0 cm3.

   (a)

   What is the density of the ring?

   [1 mark]

   • A19.3 g/cm3
   • B77.2 g/cm3
   • C2.0 g/cm3
   • D0.05 g/cm3

   (b)

   Why does the jeweller lower the ring into a measuring cylinder of water to find its volume, rather than measuring its dimensions with a ruler?

   [1 mark]

   • ABecause the ring must be cleaned first
   • BBecause water changes the mass of the ring
   • CBecause rulers cannot measure small objects
   • DBecause the ring is an irregularly shaped object

   (c)

   Describe how the jeweller would use the measuring cylinder to find the volume of the ring.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   After an oil spill at sea, engineers note that the oil (density approximately 800 kg/m3) does not mix with the seawater (density approximately 1030 kg/m3).

   (a)

   What will happen to the oil?

   [1 mark]

   • AThe oil will mix evenly through the seawater
   • BThe oil will sink below the seawater
   • CThe oil will float on top of the seawater
   • DThe oil and seawater will form a solid layer

   (b)

   A small block of plastic with a density of 1200 kg/m3 is dropped into the floating layer of oil. What will happen to the block?

   [1 mark]

   • AIt will float on top of the oil
   • BIt will sink through the oil and through the seawater to the bottom
   • CIt will float at the boundary between the oil and the seawater
   • DIt will dissolve into the seawater

   (c)

   Explain, in terms of density, why the oil floats on top of the seawater rather than sinking or mixing evenly through it.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A technician has a regular metal cube of side length 4.0 cm and mass 288 g, and also has an irregularly shaped stone of mass 175 g that sinks in water.

   (a)

   Describe how the volume of this cube could be found without using a measuring cylinder, and calculate its density.

   [3 marks]

   (b)

   The technician also has an irregularly shaped stone of mass 175 g, which sinks in water. Describe an experiment, using a displacement (eureka) can and a measuring cylinder, to determine the density of the stone, given that lowering the stone into the full displacement can causes 70 cm3 of water to overflow into the measuring cylinder.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A minerals processing plant uses density measurements both to test the density of liquids used in the plant and to separate two types of rock fragments, rock A (density 2200 kg/m3) and rock B (density 3100 kg/m3), using a liquid of intermediate density, 2600 kg/m3, in which the fragments do not dissolve.

   (a)

   Describe, in detail, an experiment to determine the density of a sample of an unknown liquid using a measuring cylinder and a balance, including how you would account for the mass of the empty measuring cylinder, and explain how the results would be used to calculate the density.

   [6 marks]

   (b)

   The processing plant separates rock fragments A (density 2200 kg/m3) and B (density 3100 kg/m3) by placing a mixture of the fragments into a liquid of density 2600 kg/m3, in which neither rock dissolves. Explain, using the given density data, what would happen to rock A and to rock B when placed in this liquid, and describe how this behaviour allows the plant to separate the two types of rock fragment.

   [6 marks]

   Total for question 4: 12 marks

End of questions