Ferrous sulphate on heating gives

Transition elements with lower oxidation states act as........

Transition metal with low oxidation number will act as

Give examples and suggest reasons for the following features of the transition metal chemistry:
$(i)$ The lowest oxide of transition metal is basic,the highest is amphoteric/acidic.
$(ii)$ $A$ transition metal exhibits highest oxidation state in oxides and fluorides.
$(iii)$ The highest oxidation state is exhibited in oxoanions of a metal.

The order of basic character for the monoxides of transition metals is . . . . .

What is the general molecular formula of the products obtained on heating lanthanoids $(Ln)$ with sulphur?