Write the molecular formulae for the following compounds
(a) Aluminium (III) nitrate
(b) Calcium (II) phosphate
(c) Mercury (II) chloride
(d) Magnesium (II) acetate
(a) Al(NO3)3
(b) Ca3(PO4)2
(c) HgCl2
(d) Mg(CH3COO)2