Answer 1

a[start:stop]
You are slicing the list from start(inclusive) to stop(exclusive!).

a[0:2] -> [1,2]
index 0 = 1
index 1 = 2
exclusive index 2, so this value is not in the list

a[2:5] -> [3,5,8]
index 2 = 3
index 3 = 5
index 4 = 8
exclusive index 5, so this value is not in the list.

I hope this explains why [2:2] returns an empty list.

About list slicing: https://www.sololearn.com/learn/JUMP_LINK__&&__Python__&&__JUMP_LINK/2453/?ref=app