What does the group number of a elements in the a/b numbering system)
tell about valence electrons?

a. the a group number tells which period the valence electrons are
in
b. the a group number tells how much mass the elements have.
c. all elements in the same a group will have the same number of
valence electrons.
d. all elements in the a group will have the same valence electrons
as the b group.

All elements in the same A group will have the same number of

valence electrons.

Explanation:

Group A has 1 valence electrons.

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons