Solution :
The formula to find the hybridisation of central atom is
$$Z = \frac{1}{2}$$ [Number of valence electrons on central atom $$ + $$ No. of monovalent atom altached to it $$ + $$ negative charge if any $$ - $$ positive charge if any]
For $$N{O_3} - Z = \frac{1}{2}\left[ {5 + 0 + 1 - 0} \right] = 3$$

For $$NO_2^ + ,Z = \frac{1}{2}\left[ {5 + 0 + 0 - 1} \right] = 2$$
.PNG)
For $$NH_4^ + ,\,Z = \frac{1}{2}\left[ {5 + 4 + 0 - 1} \right] = 4$$