\(n_{NaOH}^{} = 0,04.0,2 = 0,008\;{\text{mol}}\)
\({\text{n}}_{H_2^{}SO_4^{}}^{} = 0,03.0,25 = 0,0075{\text{ mol}}\)
\(2NaOH + H_2^{}SO_4^{} \to Na_2^{}SO_4^{} + 2H_2^{}O\)
\({\text{ }}\frac{{0,008}}{2}\;{\text{ < }}\frac{{0,0075}}{1} \to \) H2So4 dư tính theo NaOH
\({\text{ 0}}{\text{,008 0}}{\text{,004}}\)
\({\text{V}}_{{\text{dd}}}^{} = 0,003 + 0,004 = 0,007l\)
\({\text{C}}_M^{} = \frac{{0,004}}{{0,007}} = 0,571M\)