Hello, 

As per your requirement, i would say that as you have got 500+  marks in obc category, and you belong from Rajasthan so it would be 50 50 chance for you to get a government seat in rajasthan but you may get it even as you have obc caste reservation for you to avail but generally its safe to score above 550 marks because rajasthan state basically has a high cut off as lot of students belong from that state.

Getting a seat in government medical college is depending on many factors like studenrs to seat ratio, cut off, reservation etc. 

The cut off as per your caste would also depend on which state domicile you have as few states havr higher cut off .So it varies from state to state.

But you have chance to get admission in your preffered college as you can avail obc reservation. 

Good luck