Hii Sir I am worried about passing in 12th grade science pcb

Well,the fever of exam is something that get on everyone's nerves.Don't panick.The results are still not out so get the negative stuffs out of your mind.If you have studied you will get marks. Instead of worrying about what your future holds,invest yourself in your present. Go through the previous year papers and atleast finish your NCERT.For Biology and Chemistry stick to NCERT and trust me Board is not going to ask beyond NCERT but yes,you need to be thorough with the concepts if you wanr to score good marks.For Physics,solve previous years question papers and practice derivation.See,some marks you get for your practicals and some you will manage to score in the exam which would  add up to  become "passing marks".So,don't lose hope.That's the only thing that will help you get through this phase.
And heaven forbids,if you fail that doesn't mean you are devoid of abilities.Take it as a lesson of life and move ahead.Though a year will be lost but there are so many students who drop years to clear competitive examinations.
Now coming to your question,you dropping a year because of any reason won't rob you of any opportunity.For MBBS or any entrance exam of graduation level you need to have passed 12th exam.For NEET you need to score minimum 50% marks.Though there would be people who would try to write you off several times yet you don't let your conviction go away.
I repeat it again,don't predict your result without even appearing for exams.Do utilise this one month that you have before boards and things will hopefully fall in place.
Moreover you mentioned that you want to do MBBS that is,you aspire to be a doctor so one thing you must know that the life of a doctor is not easy.So,just like a doctor you also be brave enough to face  challenges.
Good luck.

Hi Sayali,
Dont worry! Everybody goes through this phase.
Just continue with your daily study. A well prepared student has nothing to fear, be it your Boards or the IAS Exam.
Here are a few steps that you should follow:-
Make a realistic revision timetable and stick to it. Start planning it well before the exams begin. Dont leave revision to the last minute.
Add headings and sub-headings, or use highlighting pens and revision cards, key words or charts - whatever works for you.
Work out what revision timetable best suits you.
If you can concentrate well in the morning then do most of your studying before lunch, not late at night when you cant concentrate. If you can study at night then study at later half of the day, but go to bed at reasonable hour and get enough sleep.
Revise very nicely since that is very important.Tryanswering questions from past exam papers or explaining tricky answers to someone else to make sure you have understood it.
If you really cannot concentrate it may be because you are tired, hungry, or just bored. Take a break and come back to it 10 minutes later. Short bursts of concentrated revision are often better than hours of staring at the same page.
Always ask for help if there are things you don't understand, and especially if you are feeling, stressed out.
Finally, never forget that there is life after revision and exams.Try to be cool in the exam.
Stop thinking about how much you are left with and keep preparing little bit every day and Im sure you will succeed and get respectable marks in Boards.
Please understand this fact:
Whatever may happen during and after the board exams, that would be no more that one episode in a long life. If you do not get good marks, or even fail to clear all subjects, you would still have the prospects of a fulfilling life ahead of you. One exam does not take that away. After the exams, study what Gautam Buddha has taught about the causes of suffering and the way to achieve lasting happiness.
As a conclusion of the above, stop thinking about what others would say. Let them live their own lives, and you focus your efforts on your life.
Hope this helps.
Good Luck!