The tetrathionate anion, $S _4 O _6^{2-}$, is a sulphur oxoanion derived from the compound tetrathionic acid, $H _2 S _4 O _6$. Two of the sulphur atoms present in the ion are in oxidation state $0$ and two are in oxidation state $+5$.
$NO_3^ - + 4{H^ + } + {e^ - }\, \to \,2{H_2}O + NO$
$C + {O_2} \to C{O_2};\Delta H = - 393\,J$
$2Zn + {O_2} \to 2ZnO;\Delta H = - 412\,J$