Which of the following species acts as a reducing agent during the working of a hydrogen-oxygen fuel cell?

Under what condition is $E_{cell} = 0$ or $\Delta_r G = 0$?

An electrochemical cell is constructed using half-cells in the direction of spontaneous change: $Fe(OH)_{2}(s) + 2e^{-} \rightarrow Fe(s) + 2OH^{-}(aq)$ $(E^{0} = -0.88 \text{ V})$ and $AgBr(s) + e^{-} \rightarrow Ag(s) + Br^{-}(aq)$ $(E^{0} = +0.07 \text{ V})$. Which of the following options is correct?

Give advantages of fuel cell.

Which of the following is $NOT$ true about a voltaic cell?

Which of the following statements is correct?