It’s relative.
In any case you need to have a strong grasp of NCERT.
If you haven’t even done NCERT, then I would say chances are extremely low.
But still, the strategy would be to focus on important concepts and reactions and to solve paper oftenly, then you might be able to join BITS PILANI.
Chances of getting CSE is nearly zero as you need at least 375/450, in a month it can’t be achieved , also when you are facing people who worked 2 years for the same target you are going to be on the soft edge.