What is the role of `HNO_(3)` in the nitrating mixture used for nitration of benzene?

Explanation

0`HNO_(3)` acts as a base in the nitrating mixture and provide the electrophilie, `NO_(2)^(+)` on reaction with `H_(2)SO_(4)` as follows
`underset("Base")(HNO_(3))+underset("Acid")(H_(2)SO_(4))rarrunderset("conjugate acid")(H_(2)NO_(3)^(+))+HSO_(4)^(-)rarrunderset("Electrophite")(NO_(2)^(+))+HSO_(4)^(-)+H_(2)O`