Can anyone explain how the bonding is formed in NO3 because I can't understand how N can satisfy electron hunger of 3 oxygen atom
Nitrogen has 5 valence atoms:
2 electrons are donated to an oxygen atom with 6 valence electrons.
2 electrons are shared with an oxygen atom to form a sigma and a pi bond.
1 electron is shared with a negatively charged oxygen atom forming a sigma bond.
Since the double bond can be anywhere, there are three possible Lewis structures. You can symbolize this by using one single drawing to show that the double bond is delocalized (that's called a resonance structure).