question_answer

The standard redox potentials \[{{E}^{o}}\] of the following systems are:

	System	\[{{E}^{o}}\](volts)
(i)	\[Mn{{O}_{4}}^{-}+8{{H}^{+}}5e\to M{{n}^{2+}}\]\[+4{{H}_{2}}O\]	\[1.51\]
(ii)	\[S{{n}^{4+}}+2e\to S{{n}^{2+}}\]	\[0.15\]
(iii)	\[C{{r}_{2}}{{O}_{7}}^{2-}+14{{H}^{+}}+6e\to \]\[2C{{r}^{3+}}+7{{H}_{2}}O\]	\[1.33\]
(iv)	\[C{{e}^{4+}}+e\to C{{e}^{3+}}\]	\[1.61\]

The oxidising power of the various species decreases in the order-

A)  \[C{{e}^{4+}}>C{{r}_{2}}{{O}_{7}}^{2-}>S{{n}^{4+}}>Mn{{O}_{4}}^{-}\]

B)  \[C{{e}^{4+}}>Mn{{O}_{4}}^{-}>C{{r}_{2}}{{O}_{7}}^{2-}>S{{n}^{4+}}\]

C)  \[C{{r}_{2}}{{O}_{7}}^{2-}>S{{n}^{4+}}>C{{e}^{4+}}+Mn{{O}_{4}}^{-}\]

D)  \[Mn{{O}_{4}}^{-}>C{{e}^{4+}}>S{{n}^{4+}}>C{{r}_{2}}{{O}_{7}}^{2-}\]