Correct statement for $3d-$ series is

In which pair of ions both are diamagnetic in nature?

The ${E^\Theta }\,\left( {{M^{2 + }}/M} \right)$ value for copper is positive $(+0.34 \,V ) .$ What is possible reason for this? (Hint: consider its high $\Delta_{ a } H^{\theta}$ and low $\Delta_{ hyd } H^{\theta}$ )

Which of the following $3 d -m e t a l$ ion will give the lowest enthalpy of hydration $(\Delta_{ hyd } H )$ when dissolved in water?

The solubility of silver bromide in hypo solution is due to the formation of :

For $M ^{2+} / M$ and $M ^{3+} / M ^{2+}$ systems, the ${E^\Theta }$ values for some metals are as follows:

$Cr ^{2+} / Cr \,-0.9 \,V$

$Cr ^{3} / Cr ^{2+}\,-0.4 \,V$

$Mn ^{2+} / Mn \,-1.2\, V$

$Mn ^{3+} / Mn ^{2+}\,+1.5 \,V$

$Fe ^{2+} / Fe\, -0.4 \,V$

$Fe ^{3+} / Fe ^{2+}\,+0.8\, V$

Use this data to comment upon:

$(i)$ The stability of $Fe ^{3+}$ in acid solution as compared to that of $Cr ^{3+}$ or $Mn ^{3+}$ and

$(ii)$ The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.