For SO42 -, sulfate ion, draw the Lewis structure (by counting valence electrons of each atom), determine the a) electron-domain geometry b) molecular geometry c) hybridization d) show the angle between the bonds in a drawing.

the bond angle is 90° since it's a tetrahedral shape.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).