Two metals `(A)` and `(B)` belong to the same group of the periodic table. Metal `(A)` forms and insoluble oxide but a soluble sulphate, metal `(B)` forms a soluble oxide but an insoluble oxide but an insoluble sulphate. Both metals `(A)` and `(B)` form hydroxides which are soluble in alkalis. `(A)` and `(B)` are