Hello,
The entrance examination of BSC(environmental science) is strictly and purely based on NCERT BOOKS(class 11th and 12th) . You should use and study from NCERT thoroughly in krder to prepare best for the entrance exam. Grasp the basic keywords and keep in mind all the important topics and the headings. Give yourself enough time to solve some sample papers which will prepare you even more for these exams.
I hope this helps,
All the best
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