The rusting of iron takes place as follows. Calculate $\Delta G^o$ for the net process in $kJ \ mol^{-1}$.
$2H^{+} + 2e^- + \frac{1}{2}O_2 \longrightarrow H_2O_{(l)} ; E^o = +1.23 \ V$
$Fe^{2+} + 2e^- \longrightarrow Fe_{(s)} ; E^o = -0.44 \ V$

The standard electrode potentials $E^o_{(I_2/I^{-})}$,$E^o_{(Br^{-}/Br_2)}$,and $E^o_{(Fe/Fe^{2+})}$ are respectively $+0.54 \ V$,$-1.09 \ V$,and $0.44 \ V$. On the basis of the above data,which of the following processes is non-spontaneous?

If the molar conductivity $(\Lambda_{m})$ of a $0.050 \ mol \ L^{-1}$ solution of a monobasic weak acid is $90 \ S \ cm^{2} \ mol^{-1}$,its extent (degree) of dissociation will be. [Assume $\Lambda_{+}^{\circ} = 349.6 \ S \ cm^{2} \ mol^{-1}$ and $\Lambda_{-}^{\circ} = 50.4 \ S \ cm^{2} \ mol^{-1}$.]

Plotting $1 / \Lambda_{m}$ against $c \Lambda_{m}$ for aqueous solutions of a monobasic weak acid $(HX)$ resulted in a straight line with $y$-axis intercept of $P$ and slope of $S$. The ratio $P / S$ is
$[\Lambda_{m} =$ molar conductivity
$\Lambda_{m}^{\circ} =$ limiting molar conductivity
$c =$ molar concentration
$K_{a} =$ dissociation constant of $HX$ ]

The equilibrium constant of a $2$ electron redox reaction at $298 \, K$ is $3.8 \times 10^{-3}$. The cell potential $E^{\circ}$ (in $V$) and the free energy change $\Delta G^{\circ}$ (in $kJ \, mol^{-1}$) for this equilibrium,respectively are

At $T(K)$,the molar conductivity of $0.04 \ M$ acetic acid is $7.8 \ S \ cm^2 \ mol^{-1}$. If the limiting molar conductivities of $H^{+}$ and $CH_3COO^{-}$ at $T(K)$ are $349$ and $41 \ S \ cm^2 \ mol^{-1}$ respectively,the dissociation constant of acetic acid is