Hi

Exampler model question paper is given in this link under each subject for physics, chemistry, maths and biology.

https://ncert.nic.in/exemplar-problems.php?ln=

You can download NCERT exemplar problems for 12th science from the below link

https://cbseportal.com/NCERT/exemplar-problems/class-12-science

Get back to me if you have any other query!