How many of these names are correct.

(i)	${\mathrm{N}}^{3-}$	$-$	Nitride ion
(ii)	${\mathrm{O}}^{2-}$	$-$	Peroxide ion
(iii)	${{\mathrm{ZnO}}_2}^{2-}$	$-$	Zincate ion
(iv)	${{\mathrm{SO}}_4}^{2-}$	$-$	Sulphite ion
(v)	${{\mathrm{NO}}_2}^{-}$	$-$	Nitrate ion
(vi)	${{\mathrm{PbO}}_2}^{2-}$	$-$	Plumbite ion
(vii)	${\mathrm{Fe}}^{2+}$	$-$	Ferric ion