The $E^{0}_{Red}$ values for $P, Q, R$ and $S$ are $-2.90 \, V, +0.34 \, V, +1.20 \, V$ and $-0.76 \, V$ respectively. The decreasing order of their reactivity is:

Consider the half-cell reduction reactions:
$Mn^{2+} + 2e^{-} \rightarrow Mn$,$E^{\circ} = -1.18 \ V$
$Mn^{3+} + e^{-} \rightarrow Mn^{2+}$,$E^{\circ} = +1.51 \ V$
The $E^{\circ}$ for the reaction $3Mn^{2+} \rightarrow Mn + 2Mn^{3+}$,and the possibility of the forward reaction are respectively:

The $E^o$ for the reduction of $NO_3^-$ ion in aqueous solution is $+0.96 \, V$. The $E^o$ values for several metal ions are given below:
$V^{2+}_{(aq)} + 2e^{-} \rightarrow V, \, E^o = -1.19 \, V;$
$Fe^{3+}_{(aq)} + 3e^{-} \rightarrow Fe, \, E^o = -0.04 \, V;$
$Au^{3+}_{(aq)} + 3e^{-} \rightarrow Au, \, E^o = +1.40 \, V;$
$Hg^{2+}_{(aq)} + 2e^{-} \rightarrow Hg, \, E^o = +0.86 \, V$
Which of the following pairs of metals is $NOT$ oxidized by $NO_3^-$ in aqueous solution?

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 ........ $V$

Give the anode reaction for an electrode of any metal $M \,|\, M^{n+}$.

Given that the standard reduction potentials for $M^{+}/M$ and $N^{+}/N$ electrodes at $298 \ K$ are $0.52 \ V$ and $0.25 \ V$ respectively. Which of the following is correct in respect of the following electrochemical cell?
$M | M^{+} || N^{+} | N$