Answer: High Reactivity
Explanation: Alkali metals are the metals which are kept in the group 1 which is also known as S -Block elements.
The electronic configuration of the elements can be written as ns1 .
These are considered to be the most reactive elements of the whole periodic table because their outermost shell has only 1 vacant electron and thus are in need of only 1 electron to complete its duplet or either they can also lose that one electron .
This the reason they can never be found pure in the nature .