hello merin rose

I hope you are doing good. I would like to tell you that their are many topics of 11th and 12th in which you should very good command for cracking the isi exam . Moreover , you have also need to learn some misclleanous hard topics from which questions are being asked repeatively . Below are list of topics which you have need to focus mainly :-

1. SET THEORY

2. COMPLEX NUMBERS

3. PERMUTATIONS AND COMBINATION

4. TRIGNOMETRY

5. DOUBLE INTEGRATION

6.  LIMIT AND CONTINIUTY

7. DIFFERENTIATION

you can refer to the following link for brief syllabus

https://engineering.careers360.com/articles/isi-exam-pattern-syllabus4

Hope you found this answer helpful. Good luck for your future