Write formulas for the following compounds:
(a) Mercury (II) chloride
(b) Nickel (II) sulphate
(c) Tin (IV) oxide
(d) Thallium (I) sulphate
(e) Iron (III) sulphate
(f) Chromium (III) oxide
(a) HgCl2
(b) NiSO4
(c) SnO2
(d) TI2SO4
(e) Fe2(SO4)3
(f) Cr2O3.