Dear Aspirant, the revised eligibility criteria for B Arch is that no candidate shall be admitted to architecture courses unless he/she has passed an examination at the end of the 10+2 scheme of examination with Physics, Chemistry and Mathematics subjects or passed 10+3 Diploma Examination with Mathematics as compulsory subject. On the other hand, it is not mandatory for appearing in JEE Main Paper 2 if you have appeared once and you are satisfied with that marks. I hope you are clear now. If you have any other doubts feel free to ask. All The Best!!!