The maximum number of covalent formed by nitrogen is

nitrogen has 5 valence electrons, three which are unpaired and one which is paired.so we can say 3 unpaired electron would form 3 bonds and 1 paired forms 1 bond.

Nitrogen has two 2s and three 2p valence electrons. By sharing the three 2p electrons, nitrogen can form three covalent bonds. For example, NH3. But still the nitrogen atom has a lone pair of electrons form 2s orbital. By donating these two electrons from lone pair, it can form one bond. For example, NH4+.
Thus, nitrogen can form four bonds.

How....Plz tell me

how ??