\(HNO_3 \to H^{+}+NO_3^{-}\\ [H^{+}]=CM_{HNO_3}=0,00125M\\ pH=-log(0,00125)=2,9\)
\(HNO3\rightarrow\) \(^{H^+}\)+ \(^{NO3^-}\)
\(0,00125\rightarrow\)\(0,00125\) \(\rightarrow\)0,00125
=> \([H^+]\)= 0,00125M
-> \(pH=-log\left(0.00125\right)\)\(\approx2,903\)