i got 68 Marks than how much the percentile will be
Hello.
I am assuming that you are asking for JEE (Mains) paper-1 March 2021. With 68 marks, your percentile is expected to be between 90.5-90.7. This is just an assumption made on the basis of previous year's data and may vary. Your percentile depends upon your raw score and also on the relative performance of the other candidates in your Session. You can go through this link for more information about your percentile and rank:
https://engineering.careers360.com/articles/jee-main-marks-vs-percentile
To know your expected rank:
To know about the colleges you can apply to based on your JEE (Mains) percentile:
https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer
I hope this helps.