What subjects are taught in IITs in Computer Science Engineering? Are they all compulsory to study or choice can be made?

The list is too long including all semesters, and it cant be put on paper or rather jotted here, so I am giving you a link of the IIT Kharagpur syllabus, hope it helps. Wish you luck with your future endeavors! https://cse.iitkgp.ac.in/?syllabus.html.