Hello student,
With a score of 490 in SC category, you have chances of procuring a seat in the government medical colleges when comparing the results of previous years. Last year, a minimum score of 457 was required to fetch one a seat in the government medical college, Dungarpur in SC category under the state quota. Also one thing to keep in mind is that scores and ranks vary each year with difficulty level of the question paper and availability of seats. However you can go through the following link to know about the cut off's and ranks for the previous years and calculate your chances of selection
https://medicine.careers360.com/articles/neet-cutoff-rajasthan
Good luck