If someone fails in second language and pases in all subjects in 10 board exams he will pass or be failed?

He will pass but the CGPA will be reduced. The CBSE marking scheme gives 10 cgpa to those who get atleast two A2 and all A1. So, if someone is failing in one subject, he would still pass tenth but i would expect a cumulative of 8.5 to 9, if he excels in the other subjects. This is are all tentative numbers, it may increase or decrease. So, just be perfect in NCERT textbooks and you will be fine.Cheers.