We subtract the enthalpies of the reactants from that of the products:

Since this is < 0, this is an exothermic reaction.
It is a solution, because it's the alloy of tin and copper
Plastic bags are made up of plastic film, non-woven fabric, or plastic textile. The molecules that are present in plastic bags are polymers. Polymers are large molecules made up of repeating units called monomers.
I know this isn't much, but I hope it helps! :)