Given at $298 \ K$: $E^\ominus_{Fe^{2+}/Fe} = X \ V$; $E^\ominus_{Fe^{3+}/Fe} = Y \ V$. The $E^\ominus_{Fe^{3+}/Fe^{2+}}$ in Volt at $298 \ K$ is given by:

The standard electrode potentials of the half-cells are given below:
$Zn^{2+} + 2e^- \to Zn$; $E^{\circ} = -0.76 \, V$
$Fe^{2+} + 2e^- \to Fe$; $E^{\circ} = -0.44 \, V$
The $EMF$ of the cell $Fe^{2+} + Zn \to Zn^{2+} + Fe$ is ............ $V$.

Standard electrode potential for $Sn^{4+}/Sn^{2+}$ couple is $+0.15 \ V$ and that for the $Cr^{3+}/Cr$ couple is $-0.74 \ V.$ These two couples in their standard state are connected to make a cell. The cell potential will be ........ $V$

Assertion : Copper reacts with $HCl$ and liberates hydrogen.
Reason : Hydrogen is present above $Cu$ in the reactivity series.

Consider the following:
$Zn^{2+} + 2e^- \longrightarrow Zn_{(s)} ; E^o = -0.76 \, V$
$Ca^{2+} + 2e^- \longrightarrow Ca_{(s)} ; E^o = -2.87 \, V$
$Mg^{2+} + 2e^- \longrightarrow Mg_{(s)} ; E^o = -2.36 \, V$
$Ni^{2+} + 2e^- \longrightarrow Ni_{(s)} ; E^o = -0.25 \, V$
The reducing power of the metals increases in the order:

The standard electrode potential $(E^\circ)$ for the reaction $Zn^{2+}_{(aq)} + 2e^- \rightarrow Zn_{(s)}$ is $-0.76 \ V$. What is the standard electrode potential for the reaction $2Zn_{(s)} \rightarrow 2Zn^{2+}_{(aq)} + 4e^-$?