Yes, previous years' question papers for the UPSC Medical Science Optional subject are available for free. These question papers are valuable resources for candidates preparing for the UPSC Medical Science Optional subject as they help in understanding the exam pattern, syllabus, and the type of questions asked in the examination.

Here are some ways through which you can access these question papers for free:

1. Official UPSC Website:
- The official website of the Union Public Service Commission (UPSC) provides a repository of previous years' question papers for various subjects, including Medical Science.
- To access these question papers, visit the UPSC website and navigate to the 'Previous Year Question Papers' section.
- Look for the question papers of the Medical Science Optional subject and download them in PDF format.

2. EduRev:
- EduRev is a popular online educational platform that offers a wide range of study materials, including previous years' question papers for UPSC examinations.
- Visit the EduRev website and search for the Medical Science Optional subject question papers.
- You can download these question papers for free in PDF format.

3. Online Forums and Groups:
- There are several online forums and groups dedicated to UPSC preparation where aspirants share study materials, including question papers.
- Join these forums or groups and request fellow aspirants for the Medical Science Optional subject question papers.
- Many aspirants are willing to share their study materials for free, including previous years' question papers.

4. Coaching Institutes:
- Some coaching institutes that specialize in UPSC preparation provide previous years' question papers as a part of their study material.
- You can visit the websites of these coaching institutes and check if they offer question papers for the Medical Science Optional subject.
- Some coaching institutes may provide question papers for free, while others may charge a nominal fee.

Please note that while accessing these question papers for free, it is essential to ensure that the source is reliable and the question papers are authentic. It is also recommended to refer to the latest syllabus and exam pattern while practicing with previous years' question papers.