When are "ого, его" pronounced as "ово, ево" and why?

Question

In "Что нового?", why is it pronounced "novava" and not "novaga"? I have been looking all over to find an explanation, but nothing I see says г can sometimes be pronounced as в.

Answer 1

In the genitive singular number of adjectives and pronouns male and neuter gender in the end is written before the vowels letter Г (although pronounced В)eg: доброго, синего, его, того, всего, моего