Hello.
before going to your question I am informing you that for having admission in the top IIT colleges firstly candidate must have at least 75% in his or her class 12th again for the admission you will have to secure a required rank in your JEE advanced exam so for the same I am providing you a link below where you can see previous year cutoff list for iist colleges which will give you a probable idea of having admission.
https://engineering.careers360.com/articles/iist-btech-admission
Best of luck.

IIST Thiruvananthapuram

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