The equivalent weight of $Na_2S_2O_3$ (Gram molecular weight $= M$) in the given reaction is $I_2 + 2Na_2S_2O_3 \rightarrow 2NaI + Na_2S_4O_6$.

Permanganate $(VII)$ ion,$MnO_4^-$,in basic solution oxidises iodide ion,$I^-$,to produce molecular iodine $(I_2)$ and manganese $(IV)$ oxide $(MnO_2)$. Write a balanced ionic equation to represent this redox reaction.

Consider the following reaction:
$xMnO_4^{-} + yC_2O_4^{2-} + zH^{+} \rightarrow xMn^{2+} + 2yCO_2 + \frac{z}{2}H_2O$
The values of $x, y$ and $z$ in the reaction are,respectively:

Observe the following reaction:
$aP_4{_{\text{(s)}}} + bOH^{-}{_{\text{(aq)}}} + cH_2O_{\text{(l)}} \rightarrow dPH_3{_{\text{(g)}}} + eH_2PO_2^{-}{_{\text{(aq)}}}$
The values of $a, b, c,$ and $d$ are respectively:

Which of the following is a redox reaction?

The number of moles of electrons required to reduce $0.2 \ mol$ of $Cr_2O_7^{2-}$ to $Cr^{3+}$ is: