Recently, my headphones mic stopped working and I figured it was probably the plug (although I'm not 100% sure). So what I've set out to do is to solder a new plug on. I asked my dad and he said the house had some solder, and even the solder iron. However, there are no lables on the solder, and my dad can't remember what type it is.
How do I identify whether it is the type used for plumbing or the electronic type? And how do I identify whether it has a hollow core of flux in it?