Hi

You can actually go for either of the options i. e giving examination of Physics and Chemistry in which you have failed  or giving examination of all the five subjects.
In both the cases you will be eligible for Neet examination as private candidates are eligible for Neet 2021 i. e those candidates you cannot clear their 12th in the first attempt and then again give 12th examination or only the subject in which they fail  and clear it.

But if in case, if your preparation is good for all the five subjects then I would suggest you to give the examination of all the 5 subjects as it would be  better  as in future you wouldn't have to club both your marksheets everywhere.

And though you are eligible for neet 2021 examination being appearing as a private candidate,  ,  this eligibility is provisional and your eligibility for admission after qualifying neet will depend upon the outcome of your  examination , that is if you will meet Neet eligibility criteria provided below :-

You should have cleared your 12th examination and after clearing it , you must have
-) at least 50 % in aggregate of PCB i.e Physics, Chemistry and Biology/Biotechnology in 12th examination if belongs to general category
-) at least 40% in aggregate of PCB if belongs to Obc/ Sc /st category
-)at least 45 % in aggregate of PCB in case of general pwd candidates to be eligible.

For detailed information about neet examination eligibility go through our page for which link is provided below; -
https://medicine.careers360.com/articles/neet-eligibility-criteria

Thank you