Marks secured by Candidates in Mathematics, Physics and Chemistry will be reduced to the base of 200 to prepare the rank lost. You can check the complete information in our article: https://engineering.careers360.com/articles/tnea-rank-list . But if you belong to General Category, you will need atleast 85%-90% in your Boards and if you belong to Reserved Categories, you need atleast 75%.

You haven't mentioned your Category. Neverthless, in 2019, the cut offs for SSN College of Engineering for CSE across various Categories have been as follows:

SC Arunthiyars: 31629

SC: 15397

ST: 20096

General Category: 729

OBC: 1566

BC-Muslims: 3605

MBC: 4002

EWS: 729

Now this is 2019 data and cut offs change every year.