In the balanced reaction $x\,MnO_4^- + y\,H_2O \to 2Mn^{2+} + 5H_2O + 9O_2 + z\,e^-$,what are the values of $x$,$y$,and $z$?

What is the equivalent weight of $IO_4^-$ when it is converted to $I_2$ in an acidic medium?

See the following chemical reaction:
$Cr_2O_7^{2-} + XH^{+} + 6Fe^{2+} \rightarrow YCr^{3+} + 6Fe^{3+} + ZH_2O$
The sum of $X$,$Y$ and $Z$ is $.......$.

In the equation,$BiO_3^{-} + 6H^{+} + xe^{-} \rightarrow Bi^{3+} + 3H_2O$. What is the value of $x$?

Identify the correct statements about the following stoichiometric equation.
$aP_4 + bOH^{-} + cH_2O \longrightarrow dPH_3 + eH_2PO_2^{-}$
$I$. $a+b+c=5$
$II$. $b+c-e=3$
$III$. The oxidation state of $P$ in $H_2PO_2^{-}$ is $+1$.

Which of the following reactions is a redox reaction?