Vamshidhar, if you opt for both B.Arch and B.Plan for JEE Mains paper 2, you will be attempting a paper of total marks as 500. The total time given will be 3.5 hours, i.e. from 2.30 pm to 6 pm.

B.Arch exam consists of 25 questions from Mathematics of 4 marks each (100 marks), 50 questions from Aptitude of 4 marks each (200 marks) and 2 drawing questions of 50 marks each (100 marks). This is of 3 hours duration.

B.Plan. also has the first two sections same- 25 questions from Maths and 50 from Aptitude, summing up to 100 and 200 marks respectively in the two sections. The third section has 25 questions from Planning of 4 marks each, i.e. 100 marks. This section is again of 3 hours duration.

Since you have selected both the papers, you will have all the 4 sections, i.e. Maths, Aptitude, Drawing and Planning. Hence the time duration for the exam has been increased from 3 hours to 3 hours 30 minutes for student opting both the papers. Hope that helps.