Nitric acid (HNO₃) is a strong acid. Hence, it completely dissociates into ions as H⁺ and NO₃⁻ in water.
The balanced equation is;
HNO₃(aq) →H⁺(aq) + NO₃⁻(aq)
The stoichiometric ration between HNO₃(aq) and H⁺(aq) is 1 : 1
Hence, the [H⁺] = 3.76 x 10⁻² M