Hydrogen
Methane
Oxygen
Carbon dioxide
1.25 V
1.50 V
1.00 V
2.00 V
lower e.m.f.
smaller quantity of electrolyte
higher internal resistance
compactness of the cell
its charge efficiency is low
it takes comparatively long time to charge a battery fully
in it, per cell charging voltage should not exceed 2.3 to 2.5 volts.
all the three problems stated above
36 No. in series
24 No. in series
18 No. in series
16 No. in series