(a) (i) For a galvanic cell, the following half reactions are given. Decide, which will remain as reduction reaction and which will be reversed to…

For a galvanic cell, the following half reactions are given. Decide, which will remain as reduction reaction and which will be reversed to become an oxidation reaction. Give reason for your answer.

$\displaystyle \mathrm{Cr}^{3+}+3 \mathrm{e}^{-} \rightarrow \operatorname{Cr}(\mathrm{s}) ; \mathrm{E}^{\circ}=-0.74 \mathrm{~V}$

$\displaystyle \mathrm{Fe}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Fe}(\mathrm{s}) ; \mathrm{E}^{\circ}=-0.44 \mathrm{~V}$

Represent the cell in which the following reaction takes place : $\displaystyle \mathrm{Mg}(\mathrm{s})+2 \mathrm{Ag}^{+}(0 \cdot 001 \mathrm{M}) \rightarrow \mathrm{Mg}^{2+}(0 \cdot 100 \mathrm{M})+2 \mathrm{Ag}(\mathrm{s})$ Calculate $\displaystyle \mathrm{E}_{\text {cell }}$ if $\displaystyle \mathrm{E}_{\text {cell }}^{\circ}=3 \cdot 17 \mathrm{~V} .(\log 10=1)$

State Kohlrausch's law. Give any two applications of it.

$\displaystyle \mathbf{\Lambda}_{\mathrm{m}}^{\circ} \mathrm{NH}_{4} \mathrm{Cl}, \quad \mathbf{\Lambda}_{\mathrm{m}}^{\circ} \mathrm{NaOH}$ and $\displaystyle \mathbf{\Lambda}_{\mathrm{m}}^{\circ} \mathrm{NaCl}$ are $\displaystyle 129$‧$\displaystyle 8$, $\displaystyle 217.4$, and $\displaystyle 108 \cdot 9 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$ respectively. Molar conductivity of $\displaystyle 1 \times 10^{-2} \mathrm{M}$ solution of $\displaystyle \mathrm{NH}_{4} \mathrm{OH}$ is $\displaystyle 9.33 \mathrm{~S} \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$. Calculate the degree of dissociation $\displaystyle (\alpha)$ of $\displaystyle \mathrm{NH}_{4} \mathrm{OH}$ solution at this concentration.