Hello Kartik,

I must first clear out that NWAC is a foreign board and requires certification like all other boards for the equivalency of its exam. As I checked for it, the certifying authority that is Association of Indian Universities recognizes NWAC certificates as valid passing of 12-year course system and thus it is certified(as your first part of the question asked). I am attaching the detailed notice number here so that you can yourself visit AIU site for the proof.

Now coming to the second part, as mentioned in the Information Brochure of JEE mains, there are a number of criteria or the board to be recognized as valid for admissions through JEE Mains. I would like to draw your attention towards point 5 on page 4 of the pdf format:

5.Any Public School/ Board/ University examination in India or in any foreign country recognized as equivalent to the 10+2 system by the Association of Indian Universities (AIU).

According to this criterion, the NWAC passing certificate is valid and makes you eligible for JEE Mains.

https://jeemain.nic.in/WebInfo/Handler/FileHandler.ashx?i=File&ii=32&iii=Y (Information Brochure of JEE Mains)

Letter No EV/II(21)/2014/ dated 04 April 2014.  (Certification notice by Association of Indian Universities).