Hello Advika !!
Aptitude test of IISER admission via SCB channel ,actually this test includes of four subjects they are biology,chemistry,physics and mathematics with equal weightage.To apply via scb, a candidate should cross the eligibility criteria ,i can provide you the sample papers of this test  and for more details just go through the link provided below:

https://engineering.careers360.com/articles/iiser-2016-sample-papers

hope this would help you a little bit.Thank you!!