Dear Aspirant, marks in mock tests and actual marks that you'll get have great differing factor - final day exam pressure. No one can tell precisely how much you'll score in final paper precisely.Mock tests help you figure out your  weak areas in the syllabus as well as in your skills ., eventually they help you out figuring out what strategy would help you at final day.Plus you have more than numerous attempts .So, the final score is sole result of what you do on the last day, how well prepared you are, how well you know your weakness and strengths , and how you strategise everything. Hope this helps . All the best!

Also you could use -

https://learn.careers360.com/test-series-jee-main-free-mock-test/

https://engineering.careers360.com/articles/jee-main-preparation-tips

Hello candidate,

The one thing which I would like to advise you is that while giving your mark examination just three techmark examination as the real examination which are going to appear in the JEE examination, this would not only help you to to remain concentrated in the final test but I will also help you to give your best in each attempt.

What has been done has already been done, so it's no use to focus on past events and whether you should strategize your planning for the future and try to give your best in your upcoming exams.

Good Luck!!