I have scored 70 marks in JEE MAINS 2015 & 90% marks in CBSE Board class 12 exam .I want to ask that there was any chance of me getting a nit in my state tamilnadu or other state?

If you belong to general then its not possible after scoring 70.Asyou achieved 90% in CBSE these universities provide you good scholarships.So its better if you join privite University.Those Universities provide you good placement oppurtunities.

Those are

1.Birla Institute of Technology
2.Manipal University
3.Lovely Professional University
4.Delhi Technological University