Respuesta :
Answer:
D. Sr < Ca < Be
Step-by-step explanation:
Ionization energy decreases from top to bottom within a Group, because the valence electrons are further from the nucleus and therefore easier to remove.
Thus, Sr has the lowest ionization energy and Be the highest.
The correct order is Sr < Ca < Be.

Answer:
D. SR < CA <BE
Explanation:
Br, Ca, and Sr are all elements of same group as they all have 2 valence electrons. As we move down in a group, a new shell is being added that increases the size of the atom. As the size of an atom increases, it is easy to remove the electron from it's outer most shell in it's gaseous state. Since, Be is above Ca and Ca is above Sr. The size increases in the order, Be < Ca < Sr. It means Be is the smallest one of them and so it's hard to remove from it's outer most shell and hence it's ionization energy is higher.