Question

A student records the mass of a piece if iron. the iron is then left outside until it rusts. What type of reaction occurs, and how does the mass of the object after rusting compare with its original mass?
a) decomposition; the mass of the rusted iron is greater
b) decomposition; the mass of the rusted iron is less
c) synthesis; the mass of the rusted iron is greater
d) synthesis; the mass of the rusted iron is less