Why is AC current used instead of DC in measuring the electrolytic conductance?

Can ${\mathrm{Fe}}^{3+}$ oxidizes bromide to bromine under standard conditions?

Given:

$$\begin{gathered} {{\mathrm{E}}^{°}}_{{\mathrm{Fe}}^{3+}|{\mathrm{Fe}}^{2+}} = 0.771 \\ {{\mathrm{E}}^{°}}_{{\mathrm{Br}}_2|{\mathrm{Br}}^{-}} = 1.09\mathrm{V} \end{gathered}$$

Is it possible to store copper sulphate in an iron vessel for a long time?

Given :

$$\begin{gathered} {{\mathrm{E}}^{°}}_{ {\mathrm{Cu}}^{2+}|\mathrm{Cu}}= 0.34 \mathrm{V} \mathrm{and} \\ {{\mathrm{E}}^{°}}_{ {\mathrm{Fe}}^{2+}| \mathrm{Fe}}= -0.44 \mathrm{V} \end{gathered}$$

Two metals ${\mathrm{M}}_1$ and ${\mathrm{M}}_2$ have reduction potential values of $-\mathrm{x} \mathrm{V}$ and $+\mathrm{y} \mathrm{V}$ respectively. Which will liberate ${\mathrm{H}}_2$from dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$.

Reduction potential of two metals M₁ and M₂ are ${{\mathrm{E}}^{°}}_{{{\mathrm{M}}_1}^{2+}|{\mathrm{M}}_1}=-2.3 \mathrm{V}$ and ${{\mathrm{E}}^{°}}_{{{\mathrm{M}}_2}^{2+}|{\mathrm{M}}_2}=0.2 \mathrm{V}$

Predict which one is better for coating the surface of iron.

Given : ${{\mathrm{E}}^{°}}_{{\mathrm{Fe}}^{2+}|\mathrm{Fe}} =-0.44 \mathrm{V}$