Are you sure about this ? Cause I had enquired in CBSE office and they have replied me that according to CBSE's examination bye laws a student failing as a regular candidate in CBSE can opt same subjects in the examination next year as a private candidate. Confusion is still there. Also, can u please tell that as per your knowledge if the case is that I can't opt physics and chemistry so what about those students who as private candidates undertake examination for improvement in all subjects , can't they take physics and chemistry as well ? Please clarify.

I am sorry Akash, I just confirmed it and you are right. So here goes the procedure--Private candidates shall not be allowed to offee such subjects for the examination which involve practical work except in the case of candidates who had failed earlier and who had put in a regular course of study at an institution affiliated to the Board in the previous academic year. That means if you have failed in the subject you can choose the same sub.   

Thanks Naveen for going to all that trouble for the query in my regard but I must convey this to you in a clear manner that I do know about the clause which you just stated in your answer. There are many subjects other than those of sciences which have practicals involved but only subjects like physics and chemistry have a laboratory practice involved as well . So , there's the confusion , CBSE's notification clearly states that failed candidates can have subjects with practicals involved if they studied it as a regular candidate . But , further ahead there's a statement that subjects like physics and chemistry can't be taken by private candidates. Now, this is very confusing , I did enquired from CBSE but they have simply stated me a bye law . They haven't specifically clarified on that part . So please , if by any means you have knowledge regarding that in particular then please tell me.

See akash don't confuse with this. If you were a regular candidate in CBSE and  you were failed and now you are applying as a private candidate  so as mentioned in the law you can take the same subjects but in any other case if you were not a regular candidate then you can't take the subjects involving practicals.