Can a professor use his/her student's work as his own work? I'm studying in a college in India. I have a course with a professor who is insisting that we submit our presentations in ppt format so that he can use them as his own ppts for his later batches. 

Is the professor allowed to do this?
All learning activities you do as a student of University should, ideally, serve one purpose &mdash; to benefit your learning. Your assessment is only a way of measuring this learning. All requirements/restrictions for assessment should, ideally, serve one purspose &mdash; fairness of assessment.

I see no problem in lecturer taking samples of student's work to teach next cohort, as long as these samples are properly attributed and/or anonymised as appropriate. The lecturer should not, of course, pass students' work as his/her own &mdash; this is plagiarism. Samples should be clearly marked as such.

However, working with samples is lecturer's job and it does not justify the restrictions imposed on the format of your assessment. 

I can understand a requirement to submit work in a format that lecturer can read &mdash; e.g. typeset not handwritten. I can understand why files need to be submitted using a universally accessible/open format, such as pdf. Forcing student into a proprietary format with no clear benefit to their learning is a bad practice. Forcing them into this format only because the lecturer does not know how to take a page out of a pdf document is very bad practice &mdash; it only demonstrates that the lecturer is incompetent with IT. The lecturer is not using their position of power and trust to the best.

Unfortunately, the world is not ideal, and in quite a few places educational system leaves to be desired. If you decide to file a formal complaint, assess your strategy and make sure it does not backfire you. It is a good idea to consult someone local &mdash; don't act simply based on advice from the Internet.