Asolution containing a mixture of metal cations was treated as follows. 1. dilute hcl was added and a precipitate formed. the precipitate was filtered off. 2. h2s was bubbled through the acidic solution. again, a precipitate formed and was filtered off. 3. the ph was raised to about 9 and h2s was again bubbled through the solution. no precipitate formed. 4. finally, sodium carbonate was added and no precipitate formed. what can be said about the presence of each of these groups of cations in the original solution?

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."