How many of the following reactions lie above the cell reaction 2H+ +2e-->H2 in electrochemical series?

At 298 K, the standard reduction potentials for the following half reactions are given. Which acts as anode with others in electrochemical cell Zn^(+2)(aq) + 2e^(-) to Zn(s), -0.762 Cr^(+3)(aq) + 3e^(-) to Cr(s), -0.740 2H^(+)(aq) + 2e^(-) to H_2(g), -0.000 Fe^(+3)(aq) + e^(-) to Fe^(2+)(aq) , +0.762

In wich of the following electrochemical cell the overall cell reaction is :

In which of the following reactions H_2 (g) is produced?

Which of the following reactions canot be a base for electrochemical cell?

2H_(2)O to 4H^(+)+O_(2)+4e^(-) Based on the above equation, answer the following questions (a) Where does this reaction take place in plants ? (b) What is the significance of this reaction ?