Pick an Element that is not equal on both sides of the equation

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.

fdvwsa gfwsargebgeebbfwfwffw gwf   vgwgw gw f gwgw fgw v v dsv dwfff

a corroding iron, if that's one of your choices