(a) State two advantages of H_2 - O_2 fuel cell over ordinary cell. (b) Silver is electron deposited on a metallic vessl of total surface area 900 cm^2 by passing a current of 0.5 amp for two hours. Calcuate the thickness of silver metal deposited, [Given : Density of silver = 10.5 g cm^(-3) Atomic mass of silver = 108 u, 1F = 96500 C mol^(-1)].

(a) State two advantages of H_2 - O_2 fuel cell over ordinary cell. (

1.	(a) State two advantages of H_2 - O_2 fuel cell over ordinary cell. (b) Silver is electron deposited on a metallic vessl of total surface area 900 cm^2 by passing a current of 0.5 amp for two hours. Calcuate the thickness of silver metal deposited, [Given : Density of silver = 10.5 g cm^(-3) Atomic mass of silver = 108 u, 1F = 96500 C mol^(-1)].
Answer» Solution :(a) (i) It is highly efficient and do not produce pollution. (ii) The `H_2O` so produced can be USED by astronauts for drinking purpose. (B) `m = Z xx I xx t` ` m = (108)/(96500) xx 0.5 xx 2 xx 60 xx 60` `= (108 xx 5)/(965 xx 10) xx 2 xx 6 xx 6 = 4.03 g` `4.03 g = V xx d` `4.03 g = V xx 10.5 g cm^(-3)` `V = "Area" xx "THICKNESS"` `V = (4.03)/(10.5)` `(4.03)/(10.5) = 900 cm^2 xx "thickness"` `"Thickness"= (0.338 cm^3)/(900 cm^2)` `= 4.26 xx 10^(-4) cm`.