What property of an element does the group number identify in a numbering system that uses "A" and "B"?
A. The number of core electrons
B. The number of inner electrons
C. The number of valence electrons
D. The electrons closest to the nucleus

C) the number of valence electrons

Explanation:

the group shows the valence electrons in the atom

eg. Na has one valence electron hence it belongs to group(I)

1 is the answer to this problem

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.