Hey,
You won't be declared passed if you have failed in Physics as it is your main subject. The 'P' in PCB stands for Physics and not Physical Education which is your optional subject and yes you do need to pass in your optional subject also to be able to get declared as passed.
The basic eligibility criteria for BA LLB(I am talking about five year integrated course) is to have passed 12th with 45 per cent aggregate marks from a recognised board and 40 per cent in case of reserved categories.
If you have failed in Physics then also you are eligible to appear for the entrance test  but you must clear the supplementary exam of Physics and at the time of counselling you must show your Marksheets to prove you have passed your 12th.
Hope this helps.
Good luck.