An acidic solution of dichromate is electrolyzed for 8 minutes using $2\mathrm{A}$  current. As per the following equation ${\mathrm{C}\mathrm{r}}_2{\mathrm{O}}_7^{2-}+14{\mathrm{H}}^{+}+6{\mathrm{e}}^{-}\to 2{\mathrm{C}\mathrm{r}}^{3+}+7{\mathrm{H}}_2\mathrm{O}$   . The amount of ${\mathrm{C}\mathrm{r}}^{3+}$ obtained was $0.104\mathrm{g}$   . The efficiency of the process (in %) is (Take: $\mathrm{F}=96000\mathrm{C}$   , At. Mass of chromium $=52$    )

At 25°C the standard emf of cell having reactions involving two electrons change is found to be 0.295 V. The equilibrium constant of the reaction is :

Kindly consider the following 

Which of the following will not give ether as product :-

Which is most reactive towards electrophilic aromatic substitution reaction :-

Which one of the following ions is the most stable in aqueous solution ?

(At. No. Ti = 22, V = 23, Cr = 24, Mn=25)