Hello ,

It mainly depends , on which mock test you are giving, if you are giving local mock-test of any local coaching institute with not great variety of question and difficulty level is low , then possibilities are less.

But , if you are giving online mock test of any popular institute of India , as they have high difficulty level of question . Then it marks is OK for you to get into NIT SILCHAR cs branch with home town and  SC category . You require atleat 15k-17k Rank for it.

But, if you take my advice , you need to focus for other top NIT's as SILCHAR is not even in top 10 NIT's . You should be targeting other NIT like Hamirpur , Allahabad , jaipur etc. as they will provide great boost to your career ,since they have high placement record .