Hi Ashish,

IISER cut off depends on your board.

The format of the aptitude test is as follows:

1. Multiple-choice questions in four subjects –- Biology, Chemistry, Mathematics and Physics with         equal weightage.

2. 15 questions in each subject (total: 60)

3. Duration: 180 minutes

4. Evaluation: +3 (correct response), 0 (no response), -1 (wrong response)

For Further details,visit the link: https://engineering.careers360.com/articles/iiser-merit-list-and-cutoff

I hope it helps.