Since you r currently appearing for ur class 12th board exams nd ur final result has not been declared yet, then u should upload ur class 10th marksheet in the "last result declaration marksheet" section. Firstly check the official ipu form instructions to see if they accept class 10 th class marksheet in case of appearing candidates or u can also contact IPU's helpline ,so that u should get the satisfied answer.

Nd let m know if want some more detailed information about itt.