Hey Aryan.

To enter into scientist field

First of all First of all after your 12 th standard , you have do your graduation in your interested field.

Once you have completed your graduation , Maters in your choosen field is compulsory.

Then opt for the Phd. in your interested resarch field.

Now speaking about exams:

Budding Scientists can take up various tests like

• ARS/NET
• Indian Institute of Space Science & Technology
• Scientist Entrance Test by DRDO

Also you can join the following institutes

• BARC
• ISRO
• DRDO
• CDAC

I am providing you a link which will direct you to page of How to be a Scientist.

Have a Good day!