Answer:
2
Step-by-step explanation:
Electron config of lithium = [He] 2s1 or 1s2 2s1
For Li to form it's cation, it has to lose a single electron from it's outermost shell
So, 1s2 2s1 becomes 1s2 as it loses that outer shell 2s1 electron to form the cation
So it's left with 2 electrons in it's 1s shell.
Answer = 2