JEE Main

It's highly impossible to get a seat of CSE in Thanjavur branch, based on your score. If you are very particular in that you have one opportunity join in any branch you got in the counselling then in the first year get CGPA above 9 you can avail your CSE seat from your 2 and onwards.

Candidates are required to either be within the category-wise top 20th percentile of successful candidates in the Class XII Board Examination or secure a 75% mark (65% for SC, ST and PwD
Candidates should be less than 25 years of age, with five-year relaxation for SC, ST, and PwD candidates. Candidates can attempt examination at most two times in two consecutive years. Candidates should have qualified the Class XII Board Examination (or equivalent) in the previous year. Candidates should not have accepted admission in any of the IIT earlier.

There is no procedure to get add score in JEE Mains if there is any mistake in the question the committee will decide whether to give add or not other wise there is no privilege to individuals.

In JEE Mains they won't consider any additional scores like intermediate, physical education previously there is a consideration for intermediate marks but now they have removed it.

Rank : 9501 -10000
mark :175 - 176
rank : 10001 - 20000
mark : 165 - 174
rank : 20001 35000
mark : 152 164
mark : 35001 - 50000
rank :140 - 151
mark :50001 75000
rank :130 - 139
mark :75001 - 98000
rank :125 129
mark : 98001 - 118000
rank : 117 - 124.

JEE Mains exam is an Entrance exam through which you get top NIT'S colleges of India For Engineering stream (B.Tech). I am sending you a link. Please check it out for all information regarding JEE Mains. link-https://www.shiksha.com/b-tech/jee-main-exam.

No, There is no chance for NIT's.