Answer:
Fusion fuses elements lighter than iron. Fission divides elements heavier than iron.
Step-by-step explanation:
Fission is when an atom undergoes breaking into new elements and some sub atomic particles and energy.
Fusion is when two small nuclei fuses to form a new element of higher atomic number.
Thus the elements which are lighter than iron will undergo fusion to form new elements.
The elements which are heavier than iron may undergo fission and divide into smaller nuclei.