\(\begin{array}{l}
a)\\
Mn{O_2} + 4HCl \to MnC{l_2} + C{l_2} + 2{H_2}O\\
{H_2} + C{l_2} \to 2HCl\\
HCl + NaOH \to NaCl + {H_2}O\\
2NaCl + 2{H_2}O \to 2NaOH + C{l_2} + {H_2}O\\
2Na + C{l_2} \to 2NaCl\\
2NaCl + {H_2}S{O_4} \to N{a_2}S{O_4} + 2HCl\\
b)\\
2NaCl + {H_2}S{O_4} \to N{a_2}S{O_4} + 2HCl\\
Mn{O_2} + 4HCl \to MnC{l_2} + C{l_2} + 2{H_2}O\\
2Fe + 3C{l_2} \to 2FeC{l_3}\\
2FeC{l_3} + Fe \to 3FeC{l_2}\\
2FeC{l_2} + C{l_2} \to 2FeC{l_3}\\
FeC{l_2} + 2NaOH \to Fe{(OH)_2} + 2NaCl\\
2NaCl + 2{H_2}O \to 2NaOH + C{l_2} + {H_2}O\\
C{l_2} + Ca{(OH)_2} \to CaOC{l_2} + {H_2}O\\
c)\\
2KMn{O_4} + 16HCl \to 2KCl + 2MnC{l_2} + 5C{l_2} + 8{H_2}O\\
C{l_2} + {H_2} \to 2HCl\\
CuO + 2HCl \to CuC{l_2} + {H_2}O\\
CuC{l_2} + 2AgN{O_3} \to 2AgCl + Cu{(N{O_3})_2}\\
2AgCl \to 2Ag + C{l_2}\\
C{l_2} + 2NaOH \to NaCl + NaClO + {H_2}O
\end{array}\)
