The correct options are
(B) The cell reaction, $Pt (s)\left| H _2(g, 1 bar )\right| H ^{+}(a q, 0.01 M ) \| H ^{+}(a q, 0.1 M )\left| H _2(g, 1 bar )\right| Pt (s)$, is an entropy driven process.
(C) For racemization of an optically active compound, $\Delta S >0$.
(D) $\Delta S >0$, for $\left[ Ni \left( H _2 O \right)_6\right]^{2+}+3 en \rightarrow\left[ Ni ( en )_3\right]^{2+}+6 H _2 O$ (where en $=$ ethylenediamine).
Battery or cell converts chemical energy of the redox reaction to electrical energy. In fuel cells (a galvanic cell), the chemical energy of combustion of fuels like H2, ethanol, etc., is directly converted to electrical energy. In a fuel cell, H2 and O2 react to produce electricity, where H2 gas is oxidized at the anode and oxygen is reduced at the cathode, and the reactions involved are:
Anode reaction: H2 + 2OH- → 2H2O + 2e-
Cathode reaction: O2 + 2H2O + 4e- → 4OH-
67.2 L of H2 at STP reacts in 15 minutes.