6 3 Genuine crystal balls are made from clarified quartz rather than glass. A student was given a small crystal ball and wanted to know whether it was genuine. (a) The mean diameter of the crystal ball was measured to be 5.06 cm and the mass of the crystal ball was measured to be 175 g. Show that the density of the material of the crystal ball is about 2600 kg m−3. (3) .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. Turn over 7 (b) The student measured the diameter of the crystal ball using vernier calipers with a resolution of 0.01 cm. She measured the mass of the crystal ball using a balance with a resolution of 1 g. The table gives the densities of clarified quartz and glass. Material Density / kg m−3 Clarified quartz 2650 Glass 2590 Determine whether the crystal ball was genuine. (6) .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. (Total for Question 3 = 9 marks)