Question

which is the most reactive alkily earth metal

Answer 1

barium is the most reactive as it in he lowest in it's group on the periodic table means it's valence electrons are the highest in energy thus unstable and will react 

Answer 2

alkaline earth metal :- if we goes down the group reactivity of metal increases .
so, in this way Radium is more reactivate element . but we know Radium is radio active metal . so, Barium is more reactive element