The mass of chemical deposited is given by Faraday's Law of Electro chemistry using:
m = (IT/F) * (M/Z) -------------- (i)
m is the mass of the substance liberated at an electrode in gms
Q is the total electric charge passed through the substance in coulombs
F = 96500 C mol−1 is the Faraday constant
M is the molar mass of the substance in grams per mol
z is the valency number of ions of the substance (electrons transferred per ion).Note: that M/z is the same as the equivalent weight of the substance altered We know, equivalent mass for a metal=atomic mass/valency.
equivalent mass of chromium=52/6=8.67.
so, using given values from questions in (i) we get:
or, 105 = (10*T/96500 ) * 8.67 so, T = 105*96500/(10*8.67) = 116868.512 seconds