Iron sinks in water and floats in mercury.
Density of Iron - 7.6g/cm3
Density of Water - 1g/cm3
Density of Mercury - 13.7g/cm3
True
Density of Iron -
7.6g/cm3 > Density of Water - 1g/cm3.
So, iron sinks in water.
Density of Iron -
7.6g/cm3 < Density of Mercury - 13.7g/cm3.
So, iron floats in mercury.