To find the standard potential of M³⁺/M electrode,the following cell is constituted : Pt/M/M³⁺(0.001 mol L⁻¹ )/Ag⁺(0.01 mol L⁻¹ )/Ag

The emf of the cell is found to be 0.421 volt at 298 K. The standard potential of half reaction M3⁺ + 3e⁻$$ \to $$ M at 298 K will be :

(Given $$E_{A{g^ + }\,/\,Ag}^ - $$ at 298 K = 0.80 Volt)

Consider the following standard electrode potentials (E^o in volts) in aqueous solution :

Element	M3+ /M	M+ /M
A1	-1.66	+ 0.55
T1	+1.26	- 0.34

Based on these data, which of the following statements is correct ?

What is the standard reduction potential (E^o) for Fe³⁺ $$ \to $$ Fe ?
Given that :
Fe²⁺ + 2e^$$-$$ $$ \to $$ Fe; $$E_{F{e^{2 + }}/Fe}^o$$ = $$-$$0.47 V
Fe³⁺ + e^$$-$$ $$ \to $$ Fe²⁺; $$E_{F{e^{3 + }}/F{e^{2 + }}}^o$$ = +0.77 V

Given
$$E_{C{l_2}/C{l^ - }}^o$$ = 1.36 V, $$E_{C{r^{3 + }}/Cr}^o$$ = - 0.74 V
$$E_{C{r_2}{O_7}^{2 - }/C{r^{3 + }}}^o$$ = 1.33 V, $$E_{Mn{O_4}^ - /Mn ^{2+}}^o$$ = 1.51 V
Among the following, the strongest reducing agent is :