Science

First of all, you need to be clear about which field you want to become Scientist in I. e. research, NASA, space etc. Basically, Scientist is a professional who studies and has expert knowledge of one or multiple natural and physical sciences. The profession needs much attention, dedication flexible personality to handle extra working hrs. According to the below profile, you should choose the course you need to pursue-
Agronomist - specializes in crops and soils
Botanist - studies the plants, herbs, etc. Geologist - specializes in the history of earth
Microbiologist - studies the microscopic animals and plants
Marine Biologist -studies ocean animals and plants.

Minimum 60% marks in 12th-
Additional eligibility Details
Mandatory Subjects : Chemistry, Physics, Mathematics, Biology/Biotechnology
Candidate must have passed 10+2 with a prescribed percentage from any recognised Board. Candidate must also have passed in Biology and Chemistry each with 60% marks. The student must have obtained 45% marks in each of the 4 subjects included in the aggregate calculation. The student must have passed in all the papers as per the respective board/council pass marks. No candidate shall be eligible for admission after a lapse of more than three years from the year of passing the previous qualifying examination. Yes, you are eligible as NIOS is a recognised board.