Hi Anu you definitely you can apply for Tamilnadu medical seats under the all India quota even when you are from Bihar. All the you need to realise that the cutoffs for all India seats is higher than the state quota cutoff and you need to have good marks in NEET if you want to apply for colleges in other states. Also only 15% seats are allocated for all India quota and hence having a good score is very much important if you want to apply for counselling round in all India quota. All the best