Hi Sneha.

Yes you can use your passport as a proof of nativity in KEAM or Kerala Engineering Architecture Medical  Exam's registration. You can use your Birth Certificate or SSLC Certificate or Passport to show your place of birth . Here is a link to Kerela government's website for more info on KEAM - https://cee.kerala.gov.in/keamonline2020/public/pdf/howtoapply.pdf

All the best.