I belong to SC category how many marks I need to secure NEET exam to get admission in govt. /Pvt College for MBBS

You haven't mentioned the State you belong to. This is important because every State has different cut offs for each Government Medical College and Private Medical College. Private Medical Colleges do not participate in All India Counselling and the seats are filled through State Counselling alone. And for appearing for State Counselling you need to hold the domicile of that particular State. Or else the only other option is through Management Quota. Under All India Quota, All the 15% of All India Quota Seats except for Jammu and Kashmir, 100% Seats at Deemed and Central Universities, IP Quota seats in ESIC Colleges, Seats at AFMC, AIIMS and JIPMER are filled by DGHS. Here you will need atleast 550 and more for seat in GMCs for All India Quota. If it is for AIIMS or JIPMER, then depending on the branch, you will need atleast 625. The 85% State Quota and Private Colleges are filled by the respective State Authorities. And there are 3 Categories in Private Medical Colleges. Again the marks you need here belong to the State you belong to. Few States like Delhi, Bihar, Maharashtra have higher cut offs than the rest of the States. Category A is the Government Quota Seats. And only candidates of the home State are eligible to apply for these seats.  B Category seats are also called Management Quota Seats and they are filled through State Counselling and the remaining seats are filled through direct Admissions by contacting the College directly provided the Candidate has registered for the respective State Counselling and has not been able to secure a seat in the Counselling. Here the fees is usually nothing less than 40 lakhs. The last Category is NRI seats Category and you cannot apply for that. So in general, you will need more than 525 for a seat even under SC Category for a seat in GMC and atleast more than 475 for a seat in a Private Medical College.