My percentile is 65 what would be mark obtained?
The calculation of the marks would be difficult as per your score. You can check the answer key which has been announced to take an Idea about the marks on the basis of your percentile score.
https://engineering.careers360.com/articles/jee-main-paper-2-answer-key
As a total No. of 1,45,386 candidates had appeared for January Session, Using the Formula (100-your score)* 1,45,386 / 100- Your Expected rank will be 50,885.
NOTE: This is only a prediction. NTA will merge the scores obtained in first and second attempt by candidates of JEE Main Paper 2 2019 for the compilation and preparation of overall merit/rank list. The rank will be released on 30th April, 2019.
Good Luck!