Em tham khảo nha :
\(\begin{array}{l}
a)\\
2NaOH + {H_2}S{O_4} \to N{a_2}S{O_4} + 2{H_2}O\\
{n_{NaOH}} = 0,2 \times 1 = 0,2mol\\
{n_{{H_2}S{O_4}}} = \dfrac{{{n_{NaOH}}}}{2} = 0,1mol\\
{C_{{M_{{H_2}S{O_4}}}}} = \dfrac{{0,1}}{{0,2}} = 0,5M\\
b)\\
{n_{N{a_2}S{O_4}}} = \dfrac{{{n_{NaOH}}}}{2} = 0,1mol\\
{C_{{M_{N{a_2}S{O_4}}}}} = \dfrac{{0,1}}{{0,2 + 0,2}} = 0,25M
\end{array}\)