Answer is: 2. Chemical reactions involve the rearrangement of electrons and 5. Isotopes of the same element behave differently in a nuclear reaction.
1) The electrons of an atom participates in a chemical reaction.
2) Chemical reactions involve the rearrangement of electrons, because there is transfer, loss, gain and sharing of electrons in chemical reactions.
3) Nuclear reactions can produce new elements, because number of protons and neutrons is changed.
4) Chemical reactions require heat or an input of energy to occur, this is activation energy.
5) Isotopes of the same element behave differently in a nuclear reaction, because isotopes have different number of neutrons, so products of a nuclear reaction is different.
