Which of the following transformations can be carried out by using $HI$ as a reducing agent,under acidic conditions?
[Given: $I_{2(s)} \rightarrow 2I^- ; E^{\circ} = 0.54 \ V$]
$(i)$ $Cu^+ \rightarrow Cu_{(s)} ; E^{\circ} = 0.52 \ V$
$(ii)$ $Cr^{3+} \rightarrow Cr^{2+} ; E^{\circ} = -0.41 \ V$
$(iii)$ $Fe^{3+} \rightarrow Fe^{2+} ; E^{\circ} = 0.77 \ V$
$(iv)$ $Fe^{2+} \rightarrow Fe_{(s)} ; E^{\circ} = -0.44 \ V$

The standard reduction potentials of $4$ elements are given below. Which of the following will be the most suitable reducing agent?
$I = -3.04 \ V$
$II = -1.90 \ V$
$III = 0 \ V$
$IV = 1.90 \ V$

$A$ gas $X$ at $1 \, atm$ is bubbled through a solution containing a mixture of $1 \, M \, Y^{-}$ and $1 \, M \, Z^{-}$ at $25 \, ^oC$. If the reduction potential of $Z > Y > X$,then

What happens to the Gibbs free energy in a spontaneous electrochemical process?

Consider the following relations for $EMF$ of an electrochemical cell:
$(i)$ $EMF$ of cell = (Oxidation potential of anode) $-$ (Reduction potential of cathode)
$(ii)$ $EMF$ of cell = (Oxidation potential of anode) $+$ (Reduction potential of cathode)
$(iii)$ $EMF$ of cell = (Reduction potential of anode) $+$ (Reduction potential of cathode)
$(iv)$ $EMF$ of cell = (Oxidation potential of anode) $-$ (Oxidation potential of cathode)
Which of the above relations are correct?

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 $2Zn_{(s)} \rightarrow 2Zn^{2+}_{(aq)} + 4e^-$?