if 2 identical bars which look as if they might be made made of iron.1 of them is a magnet whilethe is a simple iron bar.

how will u find out which one is the magnet?

Magnet attracts material made up of iron. So we will bring an object  made up of iron like iron nails etc. close to both the bars. The bar that will attract these nails will be made up of magnet and the other one is made up of iron.