CSIR NET , ISRO and GATE exams are three best exams to become a scientist.

In India,  today more than thousand positions are created for scientists every year.
Today a career in R& D (science & Engineering) is not only highly rewarding profession in India but also one of the most ideal platform to design technologies that you want around you. Research as a profession is for those who want to transform tomorrows technologies and want to create life-changing technologies. A scientist is a person engaging in a systematic activity to acquireknowledgethat describes and predicts the natural world.
In India, a scientist typically finds a research job in-

• CSIR Net Labs
• DRDO
• ISRO
• BARC

Some of the govt labs

• The basic pre-requisitesto even apply to these places for an entry level scientist job is:

You must have the good marks in the MSc
You must completed the Mtech or the PhD in the relevant field of interest.
research output, i.e. research papers.
To become a scientist you must give the following level of exams.
Some of the institute conduct the own entrance test like:
BARC
IISc
TIFR
Common entrance test jointly conducted by 23 research institutes in Physics, Chemistry and computer science that is JEST.
You can also fight for the CSIR NET Exam. After qualifying this exam you can work under the top 32 research labs in India, under the top scientist of INDIA.
All the best.