The 2nd one I believe
Answer- 2nd
There are seven periods with eighteen columns in the periodic table.
I have attached the answer. hopefully, i read the problems correctly. let me know if I did not.
both problems are an example of beta decays. when an atoms' atomic number is increased by one. this is symbolized with -1 e
Answer:
atom is the smallest unit of matter that has the characteristic properties of a chemical element.