Which of the following statements provides the best explanation for the many chemical similarities between two elements in a main group? (note: only one answer (a) they have similar atomic mass values. (b) both have the same number of valence electrons. (c) they have the same number of protons. (d) they are in the same period.

(b) Both have the same number of valence electrons.  

Step-by-step explanation:

We find the most striking chemical similarities between two Main Group elements when they are in the same Group of the Periodic Table.

Elements in the same Group have the same number of valence electrons.

(a) is wrong, because elements in the same group have different masses.

(c) is wrong, because atoms with the same number of protons belong to the same element.

(d) is wrong, because elements in the same Group must be in . different Periods.

b is the correct