Answer :
The group of elements which have the lowest ionization energy are the alkali metals. The alkali metals (Group 1) are the group which has a single electron in their outermost shell.
Answer: Group-2
Explanation:
Group -2 elements may have the lowest second ionisation energy because they contain two electrons in their outermost orbit. The loss of the second valence electron makes them attain a stable inert gas configuration.