Đáp án:
\(\begin{array}{l}
{C_M}NaOH = 5M\\
{C_M}HCl = 2,5M
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
2Na + 2{H_2}O \to 2NaOH + {H_2} \\
NaOH + HCl \to NaCl + {H_2}O\\
{n_{Na}} = \dfrac{{23}}{{23}} = 1\,mol\\
{n_{NaOH}} = {n_{Na}} = 1\,mol\\
{C_M}NaOH = \dfrac{1}{{0,2}} = 5M\\
{n_{HCl}} = {n_{NaOH}} = 1\,mol\\
{C_M}HCl = \dfrac{1}{{0,4}} = 2,5M
\end{array}\)