List the following metals co, ni, k, pt, ba, and hg, in order of increasing activity (least active to most active)

The least active metal is K+ because it reacts with water. Ba also is less active for the same scientific reason. Co is reactive with acids, making them more active than K+ and Ba. Ni is more active than Co when reacting to acids. Hg is highly reactive. However, Pt is the most active.