What would happen if Mark Zuckerberg was born in India?
What would have happened if Mark Zuckerberg had born in India?
Which one of these two is correct ?
Mark Zuckerberg was born in the past, so you would use past tense:
What would have happened if Mark Zuckerberg had been born in India?
Asking what would happen if a certain event occurred means that the event hasn't happened yet.
This one is what you typically find in your typical English grammar textbook (and that's perfect grammar):
What would have happened if Mark Zuckerberg had been born in India?
But more colloquially (daily English), you can just say:
What would have happened if Mark Zuckerberg was born in India?