The efficiency of a fuel cell is given by

E^o_Fe²⁺/Fe = $$-$$ 0.441 V and E^o_{Fe³⁺/Fe²⁺} = 0.771 V, the standard EMF of the reaction Fe + 2Fe³⁺ $$ \to $$ 3Fe²⁺ will be

A hypothetical electrochemical cell is shown below.

$$A\left| {{A^ + }\left( {xM} \right)} \right|\left| {{B^ + }\left( {yM} \right)} \right|B$$

The emf measured is + 0.20 V. The cell reaction is

4.5 g of aluminium (at. mass 27 amu) is deposited at cathode from Al³⁺ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from H ions in solution by the same quantity of electric charge will be