Density
2 marks · NormalExplain why a solid iron nail sinks in water but a solid block of wood floats.
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Must show: Iron is more dense than water so it sinks, Wood is less dense than water so it floats
Also accept: Both points made in either order; reference to density comparison
Common mistakes: Explaining in terms of weight only
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Identifies that iron is more dense than water and sinks.
B2 · 1 mark · Identifies that wood is less dense than water and floats.
Worked solution
A solid iron nail sinks because its density is greater than that of water.
A wooden block floats because its density is less than that of water.