Answer:
D. They have the same number of valence electrons
Explanation:
In order to answer this question we need to understand the following.
- Valence electrons refers to the outermost electron(s) in the outermost energy level of an atom.
- Elements in the same group in the periodic table have the same number of valence electrons. For instance, group 2A elements have 2 valence electrons.
- The reactivity of elements in the periodic table is based on the number of valence electrons and the ease of gaining or losing electrons.
- Elements in the same group have similar valence electrons and therefore share similar chemical properties such as reactivity.
- Hence, elements in the same group have same number of valence electron and will thus have similar reactivity.
