Answer
$\therefore$ Be < B < Li is the right answer
Work Step by Step
Atomic Number of Li = 3 electronic configuration = $1s^22s^1$
Atomic Number of Be = 4 electronic configuration = $1s^22s^2$
Atomic Number of B = 5 electronic configuration = $1s^22s^22p^1$
So to the order of elements in the increasing ${I.E}_2$ will be
Be < B < Li
