I think the answer to e is the fourth flask cause the solution that produces more ions will exhibit the greatest depression of the freezing point, leading to the lowest freezing point which the 3rd flask will produce 3 iones, the 1st flask will produce 2 iones, CH30H will not dissociate into ions, and the fourth flask will have a low dissociation constant.
The 4th flask has the lowest pH
I think the answer to c is low pH means the solution is acidic; if the solution is acidic, that means that there are hydronium ions in solution (H3O+).
I think the answer to a is all of the flasks except the 2nd flask
The 3rd flask is most likely to react with an Arrhenius acid to form a salt and water