What are anode and cathode of ${\mathrm{H}}_2-{\mathrm{O}}_2$ fuel cell? Name the electrolyte used in it. Write electrode reactions and net cell reaction taking place in the fuel cell.

Identify oxidising agents and arrange them in order of increasing strength under standard state conditions. The standard potentials are given in parenthesis.

$\mathrm{Al} (-1.66 \mathrm{V}), {\mathrm{Al}}^{3\oplus } (-1.66 \mathrm{V}), {\mathrm{Cl}}_2 (1.36 \mathrm{V}), {\mathrm{Cd}}^{2\oplus } (-0.4 \mathrm{V}), \mathrm{Fe} (-0.44 \mathrm{V}), {\mathrm{I}}_2 (0.54 \mathrm{V}), {\mathrm{Br}}^{\ominus }(1.09 \mathrm{V})$.

Which of the following species are reducing agents? Arrange them in order of increasing strength under standard state conditions. The standard potentials are given in parenthesis.

$\mathrm{K} (-2.93 \mathrm{V}), {\mathrm{Br}}_2 (1.09 \mathrm{V}), \mathrm{Mg} (-2.36 \mathrm{V}), {\mathrm{Ce}}^{3\oplus } (1.61 \mathrm{V}), {\mathrm{Ti}}^{2\oplus }(-0.37 \mathrm{V}), {\mathrm{Ag}}^{\oplus } (0.8 \mathrm{V}), \mathrm{Ni} (-0.23 \mathrm{V})$

Predict whether the following reactions would occur spontaneously under standard state conditions.

a. $\mathrm{Ca}\left(\mathrm{s}\right)+{\mathrm{Cd}}^{2\oplus }\left(\mathrm{aq}\right)⟶{\mathrm{Ca}}^{2\oplus }\left(\mathrm{aq}\right)+\mathrm{Cd}\left(\mathrm{s}\right)$

b. $2{\mathrm{Br}}^{\ominus }\left(\mathrm{s}\right)+{\mathrm{Sn}}^{2\oplus }\left(\mathrm{aq}\right)⟶{\mathrm{Br}}_2\left(\mathrm{l}\right)+\mathrm{Sn}\left(\mathrm{s}\right)$

c. $2\mathrm{Ag}\left(\mathrm{s}\right)+{\mathrm{Ni}}^{2\oplus }\left(\mathrm{aq}\right)⟶2{\mathrm{Ag}}^{\oplus }\left(\mathrm{aq}\right)+\mathrm{Ni}\left(\mathrm{s}\right)$