Hi.

It depends on how you want to become a scientist and under what field you wish to work for. To become a scientist you will need to clear all sorts of national level examinations. For example you can become an scientist in R&D after getting your B.Tech degree for that you need to crack JEE Mains with good rank OR you could be a scientist that work in the field of Biology then you need B.Sc and M.Sc biology or MBBS Degree if you will. Furthermore, to join IISER you can give their entrance exam or join through KVPY Examinations. There are lots of options, so i would suggest you to get a clear heading through a counsellor or an elder with genuine information in this matter then if you have a specific question then please feel free to comment.

BEST OF LUCK