Question

what is the primary result of a fisson reaction ?

1 conversion of mass to energy
2 conversion of energy to mass
3 binding together of two heavy nuclei
4 binding together of two heavy nuclei

i think its 4, am i right ?

Answer 1

3, and 4 are identical, and wrong.

1 happens, and it is an astounding result. Normally, in commercial applications, it is the primary reason for the reaction.

So all this boils down to what is meant by Primary: Some would say energy, some would say radioactive products, and some would say a mess of lighter nuclei. It would be most unusual for fission to produce just two lighter nuclei, although on animations, it makes drawing it easier. But when a large nuclei "splits", it splits into several messy pieces, some of which split again, and most of the pieces are unstable, and decay into other elements over time.