Question

The metals of Group 2 from top to bottom are : Be, Mg, Ca, Sr, Ba. Which of these metals will form ions most readily and why. 

Answer 1

Ba i.e. barium is your answer.
As ons goes down the group the ionisation potential decreases and so the metal losses electrin easily.

Answer 2

Barium will form ions most readily because Barium, whose chemical symbol is Ba, is one of the alkaline metals and we know that the chemical reactivity of metals increases as we move from top to bottom in a group.

Chemical reactivity is the tendency to of elements to form ions by gaining or losing the electrons from their valence or penultimate shell or energy level.