Hello Shanu,
Admission into majority of Engineering colleges in India for a Bachelor of Technology degree
Depends upon your rank in the respective competitive exams that the institute considers.

Every state has it's Common Entrance Test Exam.
And The JEE Main (&Advanced) exam.
Also, some institutes may have their own specific Entrance exams.
Academic Eligibility for applying depends upon the institute. They have different minimum 12th Board marks requirement.
So, the colleges you can get into really depends on all the above factors.
What is your location preference?
What are the exams that you've given?
How much score have you got (or expected)?
These questions will decide your admission.
Hope this helps :)
Best of luck!