Hi aspirant!
You're a high school student now and being in 11th in science stream, you need to encourage yourself to practice harder. This is a class for basics in your newly introduced subjects and their vast knowledge.
The most important base for 12th and it will effect your future studies so you need to take that carefully.

While you discover about the subjects, try to inculcate the most queries and answers from your NCERT textbook itself. Practice all the HOTS and back exercise questions specially chemistry since majorly the cbse exams consists of ncert questions.
Other textbooks that you may follow can be the assignments you are assigned at your coaching centre.

Don't worry brat, if you do such basic steps and practice whole heartedly, you'll succeed for sure.