why???????

think about what happens along the group...

Follow sky...

:P [dun call me star naa re... woh naam change karke musibat me phans gayi... abhi edit nahi hora :'(]

Fr the lowest oxide, the metal wud be in its least Oxid.ⁿ state....tht means now it cannot reduce itself further, but can only oxidise itself n tht wud be possible by donating electrons (Hence acting as a Lewis Base)

Same way v can see fr the highest one..... it can only reduce itself by gaining electrons which wud make it a lewis acid....

n the magnitude of these charachters wud depend on as to which oxid.ⁿ state is stabler fr the particular metal....(like @ the bottom, lower oxid.n states r stabler due 2 inert pair eff. etc....)

i feel this is a correct explanation !

I dont have the answer....so i will wait for others too to reply

With the inc in the oxn states of a given transition metal, the covalent character of it's compound inc and thus acidic character also inc.
The basic and amphoteric oxides dissolves in non - oxididsing acids and hexaaquo ions [M (H20) 6 ] n+ . The acidic oxides like CrO3 and Mn2O3 dissolves in water to form the oxoacids. These oxides also reacts with bases to form oxosalts.

As we move along a given transition series, +2 oxn state of the metal becomes more and more stable and hence the tandency of these metals to lose electrons inc , hence, reducing nature of the metal oxide inc.