The standard reduction potentials at $25°\mathrm{C}$ of ${\mathrm{Li}}^{+}|\mathrm{Li},$ ${\mathrm{Ba}}^{2+}|\mathrm{Ba}, {\mathrm{Na}}^{+}|\mathrm{Na}$ and ${\mathrm{Mg}}^{2+}|\mathrm{Mg}$ are $-3.03,-2.73,-2.71$ and $-2.37 \mathrm{V}$
respectively. Which one of the following is the strongest oxidising agent?

Given : $\mathrm{E}°\left({\mathrm{Cu}}^{2+}\mid \mathrm{Cu}\right)=0.337\mathrm{V}$ and $\mathrm{E}°\left({\mathrm{Sn}}^{2+}\mid \mathrm{Sn}\right)=-0.136\mathrm{V}$. Which of the following statements is correct?

Consider the following sets:

Blue colour solution changes to colourless (or fades) in :

Consider the following sets

colourless solution changes to blue coloured solution in: