What is electrode potential?

Given below are half-cell reactions:
$MnO_{4}^{-} + 8H^{+} + 5e^{-} \rightarrow Mn^{2+} + 4H_{2}O$,
$E^{o}_{MnO_{4}^{-} / Mn^{2+}} = +1.510 \, V$
$\frac{1}{2} O_{2} + 2H^{+} + 2e^{-} \rightarrow H_{2}O$,
$E^{o}_{O_{2} / H_{2}O} = +1.223 \, V$
Will the permanganate ion,$MnO_{4}^{-}$,liberate $O_{2}$ from water in the presence of an acid?

For the given cell reaction $Fe^{2+}_{(aq)} + Ag^{+}_{(aq)} \rightarrow Fe^{3+}_{(aq)} + Ag_{(s)}$,the standard cell potential is:
Given:
$Ag^{+} + e^{-} \rightarrow Ag \quad E^0 = x \ V$
$Fe^{2+} + 2e^{-} \rightarrow Fe \quad E^0 = y \ V$
$Fe^{3+} + 3e^{-} \rightarrow Fe \quad E^0 = z \ V$

Review the $SRP$ (at $25\,\text{°C}$) data in acidic medium:
$Ti^{4+} + e^- \to Ti^{3+}, \, E^o = -x \text{ V}$
$Fe^{3+} + e^- \to Fe^{2+}, \, E^o = -y \text{ V}$
where $x < y$,point out the wrong statement.

$A$ cell reaction is spontaneous when:

Identify the reaction from the following that occupies the top position in the $EMF$ series (standard reduction potential) at $298 \; K$.