Hello Parthib,

As we know that JEE-Mains is one of the tough competitive exams which needs hard work to get success in it. In order to achieve AIR(All India Rank) under 1000 you need to score 260+ marks out of 300.

Now, let's talk about IISER (Indian Institute of Science Education and Research), it is one of the most prestigious institutes of India. You need good score in JEE-Advance examination to get admission into this college.

For more details like admission process, facilities, etc. in IISER, Mohali check out the given link :

Link: https://www.careers360.com/university/indian-institute-of-science-education-and-research-mohali

Hope this helps you.

All The Best!!