\(Mn{O_2}\, + \,4NaCl\, + 4{H_2}S{O_4}\, \to \) \(MnC{{l}_{2}}\,+\,4NaHS{{O}_{4}}\,+\,2{{H}_{2}}O\,+\underset{\begin{smallmatrix}
(Z) \\
pungent
\\
gas
\end{smallmatrix}}{\mathop{\,C{{l}_{2(g)}}}}\,\)
$FeCr _{2} O _{4}+ Na _{2} CO _{3}+ O _{2} \rightarrow A + Fe _{2} O _{3}+ CO _{2}$
$A + H ^{+} \rightarrow B + H _{2} O + Na ^{+}$