There are a number of factors accountable for determination of cutoffs and ranks like:

Number of students appearing for exam

Number of students qualifying the exam

Total marks obtained

Difficulty level of exam

Availability of seats

Number of universities participating etc.

That being said, the general cutoff/rank goes like-

500<  Rank from 1 to 700

475-499 Rank from 700 to 1050

399-475 Rank from 1050 to 7050

350-399 Rank from 7050 to 16000

300-349 Rank from 16000 to 25000

250-299 Rank from 25000 to 30000

below 249 Rank above 30000

To get into a government college, especially for a more popular course like Computer Science you should look for rank under 200. For Mechanical Engineering, look for rank under 300 to 400. And likewise.