Science

To get admission in B.K, you'll need around 75 percentile in your CMAT.

I think I won't be wrong if I say that you can still score well if you take Maths as your subject in 11th. You should pay most attention to what you are taught. Also, figure out your doubts when you solve exercises and then discuss them with your teachers. There are many IITians who were very poor i

I think, first of all, you should practice your NCERT completely. Don't leave any question from NCERT. Once you are done with NCERT, then you should go with other books like RD Sharma or Together With or any other that you prefer. But give first priority to your NCERT textbook.

Firstly, register yourself in Naukri. Com if you're a fresher. So you can get some the latest job openings which are up to your choice of job package you want to have. You can look up to job of your choice in biochemistry department in the following website:
https://www.naukri.com/lab-technician-jobs

As per your marks, you have cleared the basic eligibility criteria for IIT.
But to get admission in IIT, you have to clear JEE-Advanced with a decent rank to get admission in your dream branch. So, all the best for future.