How do i know if a reaction is exo/endothermic?? help please.

Can someone me with these questions plz.

The nuclear fission process releases neutrons and question 27 options: alpha particles electrons energy beta particles

If it is an isoelectronic series select true, if not select false. o2-, s2-, se2-, te2- na+, k+, rb+, cs+ n3-, p3-, as3-, sb3- ag, cd+, sn3+, sb4+ f-, cl-, br-, i- f-, ne, na+, mg2+ s2-, s, s6+