howmany %need in +2

Minimum 50%.

The minimum marks in the qualifying examination (MMQE) for writing the JEE will depend on the applicant's category. For the applicant belonging to general (GE) and Other Backward Classes (OBC) categories the MMQE is 60%. For the applicant belonging to SC and ST the MMQE is 55% For all persons with

just a first class score at 10+2 is needed

you will have to give entrance test for take admission in IITs if you have first divison