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You can fill the form of bsc nursing while pursuing 12th but at the time of admission you must submit the documents of 12th that is you must passes your 12th.
Yes. A student pursuing his/her 12th can apply for B.Sc entrance examination and fill in the relevant application form. You should be atleast 17 years on a set date and you should have studied Biology, Physics and Chemistry in your 12th to be eligible for studying B.Sc.