Outline the reasons why the element mercury (Hg) is not a suitable candidate for the material responsible for producing the magnetic dipole fields in the four giant planets. (The relative abundance by number of Hg is 12 on a scale that sets the abundance of H at 10¹². On this scale the relative abundances of some common elements are Si 3.5 × 10⁷, N 1.1 × 10⁸, Fe 3.2 × 10⁷. Note that the density of Hg is about 1.36 × 10⁴ kg m^－3.)