The standard electrode potentials $(E^{0}_{Red})$ of four elements $A, B, C,$ and $D$ are $-3.05 \ V, -1.66 \ V, -0.40 \ V,$ and $0.80 \ V$ respectively. Which of the following is the most reactive?

What happens to the Gibbs free energy in a spontaneous electrochemical process?

If in a galvanic cell,the hydrogen half-cell is the anode on the left side,what is the sign of the standard potential of such a galvanic cell? Give an example.

If $E^{0}_{Ag^{+} | Ag} = 0.80\, V$ and $E^{0}_{Cu^{2+} | Cu} = 0.34\, V$,then the standard cell potential of the cell formed by these electrodes is ........... $V$.

Aluminium displaces hydrogen from dilute $HCl$ whereas silver does not. The e.m.f. of a cell prepared by combining $Al/Al^{3+}$ and $Ag/Ag^{+}$ is $2.46 \ V$. The reduction potential of silver electrode is $+0.80 \ V$. The reduction potential of aluminium electrode is $........... \ V$.

$E^o_{cell}$ for the cell: $Pt_{(s)} | H_{2(g)} | HCOOH_{(aq)} || CH_3COOH_{(aq)} | H_{2(g)} | Pt_{(s)}$ at $25^oC$ is ............ $V$. ($K_a$ of $HCOOH = 2.4 \times 10^{-4}$,$K_a$ of $CH_3COOH = 1.8 \times 10^{-5}$,$\log 2 = 0.3$,$\log 3 = 0.477$,$\frac{2.303RT}{F} = 0.059$ or $0.06$)