Which of the following occur during all nuclear reactions? check all that are true

a. an atom splits into smaller atoms.

b. an atom becomes a new element.

c. an atom’s nucleus is affected.

d. some mass is turned into energy.

True answers would be B, C, and D.

A:  This statement is not true. The "splitting" that is seen in nuclear reactions is shown in the nucleus of an atom, not the atom itself splitting.

B: This statement is true, see the equation I created below, which illustrates the creation of oxygen atoms.

4He^2+14N^7→17O^8+1H^1

C: This statement is true. In nuclear fission, one form of a nuclear reaction, an atom's nucleus is split into smaller parts, which quite obviously affects the nucleus, seeing as it is now in several parts.

D: This statement is true. We know this because of the well known equation created by Einstein, E = mc2. In a nuclear reaction, mass is not strictly conserved.  Some of the mass is converted into energy.

I hope this was helpful! Let me know if you need any further explanation. I tried my best to thoroughly explain this, as I have background in this sort of education.

the fossil record provides evidence of a common ancestor to many species.