Category is dependent upon the rank and the preference of subject and the campus. You’ve said Vellore and 70k rank, so the third criteria, I’ll try to assume different scenarios only about vellore campus:
- any branch related to CSE/IT, all categories will be filled around 40k rank.
- You might have a shot at mech/ECE/EEE, very unlikely though, but still might make it in category 3/4/5.
- Branches like Civil or production, again not very likely but even category 2 might be possible.
Hope this helps! All the best.