is NCERT and NCERT exemplar enough for BITSAT chemistry?
If it's chemistry I would say ncert should be enough ( though it would be wise if u study organic from a different bookin addition to ncert ).
Maths is more of a practice based subject, so practice from different books (including the ones for iit).
For physics I would recommend to go through the basics in ncert (something I didn't do and trust me I regret it) and then practice from different books including the school ones.
The questions in bitsat r very easy ( most of them r formula based) so it's the time management u need to work at.
Buy a bitsat book and practice as many mock tests as possible then identify ur mistakes.
Ps - all the concepts will be there in ncert, but just studying ncert will not help to much.
All the best!
Hope this helps you!
Regards!