Shashi, you haven't mentioned any college or entrance examination in particular. But in general, to be eligible for studying B.Tech, you should have completed your 12th with Physics, Chemistry and Mathematics as your core subjects. Instead of Chemistry, you can have any vocational subject. Students studying and preparing for their 12th exams also can study B.Tech. There are various entrance examinations in India for B.Tech and you can check the list at: https://engineering.careers360.com/articles/top-engineering-entrance-exams-in-india . Now the basic eligibility criteria like the minimum age and subjects remain the same but the minimum aggregate that you need will be different for each entrance examination.