sentences: a hammer often is made of metal & when a metal rusts , that metal becomes flaky on the surface -> when a nail rusts, the nail will becom flaky on the bottom when a hammer rusts, the hammer will becom flaky on the surface  when a nail rusts, the nail will becom flaky on the bottom & kim's hammer is flaky on the surface -> the hammer has rusted the hammer has rusted  the hammer has rusted & quality forming is a mean of physical static -> the hammer has undergone a chemical change