A ‘gold medal’ used in events such as the Olympic Games is made from a silver–nickel alloy with a coating of a gold–silver alloy.
The mass of the medal is 256 g, of which 24.0 g is the mass of the coating.
The density of the silver–nickel alloy is 10.0 g cm–3 and the density of the gold–silver alloy is 16.0 g cm–3
What is the volume of the medal?

Answer:

11) D

Mass of non-coating material = 256-24 = 232 g Density of non-coating material = 10 g cm-3 Volume = Mass / density = 232 / 10 = 23.2 cm3
Density of coating material = 16
Volume = 24/16 1.5 cm3
Total volume 23.2+1.5 = 24.7 cm3