I expect 200 marks in jee main paper 2 April 2019 what would be my percentile ?

Hi Aastha, congratulations for your score, but we cannot predict your percentile on the basis of your score as your percentile will be calculated after normalisation. NTA will calculate your percentile by considering various factors such as the difficulty level of your paper and not  just your marks. So I would suggest you to wait for the announcement of your result. If you want any other information about the normalisation procedure or how your rank and percentile will be calculated you can check out the following link-

https://engineering.careers360.com/articles/jee-main-normalisation-process-how-scores-are-calculated

I hope this would have helped you. All the best!