alkenes and alkynes

Hello,

I am having trouble figuring out the difference in products when an
alkyne is treated with KmNO4 (and acid)
and when an alkene is treated with the same.

Also, what is a goos way to tell by inspection what substances will
dissolve in HCl vs NaOH vs water?
Is it true that anything that dissolves in water will also dissolve in
acid, and vice versa?

Any thoughts?

Thanks
Sarah