\(-log\left[H^+\right]=3\Rightarrow log\left[H^+\right]=-3\)
\(\Rightarrow\left[H^+\right]=10^{-3}\)
\(pH=-log\left[H^+\right]\)
=>\(log\left[H^+\right]=-3\)
=>\(\left[H^+\right]=10^{-3}=0,001\)
\(pH=-log\left[H^+\right]\\ \Rightarrow\left[H^+\right]=10^{-3}\left(M\right)\)