Question

Help with one chemistry question?

Answer 1

The first one is wrong, because the properties in a group are similar, not in a period. 

The second one is wrong. Elements do not get smaller as they move downward a group. 

The third one is correct, because the valence electrons determine a property of a element. 

Answer: thrid one

Answer 2

The third answer would be the most accurate answer for this particular question. Elements in group 8A ARE the most reactive properties on the periodic table. Hope this helps you!