Đáp án:

\(\begin{array}{l}
50,A\\
51,A\\
55,B\\
56,A\\
57,B\\
59,D\\
60,B\\
65,B
\end{array}\)

Giải thích các bước:

65,

\(\begin{array}{l}
NaOH + HCl \to NaCl + {H_2}O\\
{n_{NaOH}} = {n_{HCl}} = 0,2mol\\
 \to {m_{NaOH{\rm{dd}}}} = \dfrac{{0,2 \times 40 \times 100}}{{10}} = 80g
\end{array}\)

60,

\(\begin{array}{l}
2KOH + {H_2}S{O_4} \to {K_2}S{O_4} + 2{H_2}O\\
{n_{KOH}} = \dfrac{{112 \times 25}}{{100 \times 56}} = 0,5mol\\
 \to {n_{{H_2}S{O_4}}} = \dfrac{1}{2}{n_{KOH}} = 0,25mol\\
 \to {m_{{H_2}S{O_4}{\rm{dd}}}} = \dfrac{{0,25 \times 98 \times 100}}{{4,9}} = 500g
\end{array}\)

59,

\(\begin{array}{l}
2NaOH + {H_2}S{O_4} \to N{a_2}S{O_4} + 2{H_2}O\\
{n_{NaOH}} = 0,5mol\\
 \to {n_{{H_2}S{O_4}}} = \dfrac{1}{2}{n_{KOH}} = 0,25mol\\
 \to {V_{{H_2}S{O_4}{\rm{dd}}}} = \dfrac{{0,25}}{2} = 0,125l = 125ml
\end{array}\)