posted by Anonymous .
You are confronted with an unknown metal, M, and need to determine its identity. Using the following information identify the metal.
M(s) Reacts vigorously with water and acid.
M(s) does not react with K+(aq)
M(s) reacts with Co+2(aq)
M(s) does not react with Ca+2(s)
M(s) reacts with Na+(aq)
A metal that reacts vigorously with water must belong to Groups I-A (alkalis) or II-A (alkaline earths). Not reacting with K+ and Ca^+2 is no help at all. Not many other species do, either. Besides, Ca+2(s) is pure nonsense. Reacting with Na+ is unlikely. Reaction with Co+2(aq) is no help either since a Group I and II metal would react with water rather than a transition metal ion.
It is not possible to give a good answer to a bad question, no matter how many times you post this.