When the following redox reaction is balanced using simplest 'natural numbers', the stoichiometric coefficient of ${\mathrm{H}}_2\mathrm{O}$ will be:
$\mathrm{Cr}(\mathrm{OH}{)}_3+{\mathrm{IO}}_2^{-}+{\mathrm{OH}}^{-}⟶{\mathrm{I}}^{-}+{\mathrm{CrO}}_4^{2-}+{\mathrm{H}}_2\mathrm{O}$

In the reaction:
$3{\mathrm{Br}}_2+6{\mathrm{CO}}_3^{2-}+2{\mathrm{H}}_2\mathrm{O}⟶5{\mathrm{Br}}^{-}+{\mathrm{BrO}}_3^{-}+6{\mathrm{HCO}}_3^{-}$

Indicate in which of the following processes the nitrogen is reduced:

Consider the reaction
$2{\mathrm{MnO}}_4^{-}+10{\mathrm{Cl}}^{-}+16{\mathrm{H}}^{+}⟶2{\mathrm{Mn}}^{2+}+5{\mathrm{Cl}}_2+8{\mathrm{H}}_2\mathrm{O}$ and select the correct statements:

What will be the value of $\mathrm{x}, \mathrm{y}$ and $\mathrm{z}$ in the following equation?

${\mathrm{x}}_2+{\mathrm{yOH}}^{-}\to {\mathrm{IO}}_3^{-}+{\mathrm{zI}}^{-}+3{\mathrm{H}}_2\mathrm{O}$

Which of the following changes does not involve either oxidation or reduction: