Respuesta :
Answer;
-Rubidium (Rb)
Explanation;
- Alkali metals are group 1 elements, they have a valency of 1 and react by loosing electrons to attain a stable configuration.
- The reactivity of alkali metals increases down the group, this is due to the increase in the number of energy levels which makes it easier for the valence electrons to be lost.
- Therefore, in our case, rubidium will be the most reactive as it contains more number of energy levels, therefore it will loose valence electron more easily compared to the other alkali metals above it in the group.