i want to study in GOVT. college... and my jee mains marks 30 so what Govt. college i get ?

I dont think so you can able to get admission at 30 marks in JEE in any government college. Check some top institute of India which conduct there own entrance tests like lovely professional university, osmania , jaypee. These universities also offer good scholarship schemes based upon 12th percentag

At this score it is difficult to get govt college , you have to apply for private college or university