To get into IIT  you have qualify two examination namely JEE MAINS and JEE ADVANCED. The syllabus for both of this exam is based on 11th and 12th and the subjects are Physics, Chemistry and Mathematics. But to score well in this exam you need to have very good foundational knowledge in these three subjects. So you should prepare your basics well mainly in Mathematics such as Trigonometry, Algebraic Equation, Mensuration, Geometry. This will help you in solving problems of physics in class 11 and 12. Apart from this you should study basic concepts well in science very well. Now if you want to start your study based on IIT and want to get some idea then Pearson publication have three books for Physics, Chemistry and Mathematics and the name of the book is 'IIT JEE Foundation series'. You can buy this book and study from it, it can give you some more basic details about the curriculum and this can really help you to build your foundation.

To know more about JEE MAINS visit the link below:

https://engineering.careers360.com/exams/jee-main

To know more about JEE Advanced visit the link below:

https://engineering.careers360.com/exams/jee-advanced

I hope this answer helps. All the very best for your future endeavors!