Oxidation is the process by which . A. an atom gains electrons
B. an atom loses electrons
C. negative ions are attracted to the anode
D. positive ions are attracted to the anode.
E. positive ions are attracted to the cathode.

because of all the things that happen around the us, many people get into arguments which sadly could get physical, but we should actually make a change for that.

you need to have a picture of the atom that way we can answer it

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.