The time required to coat a metal surface of `80 cm^(2)` with `5 xx 10^(-3) cm` thick layer of silver (density `1.05 g cm^(-3)`) with the passage of `3A` current through a silver nitrate solution is:

Options

A. `115` sec
B. `125` sec
C. `135` sec
D. `145` sec

Answer

B

Explanation

Weight of `Ag` required
`= 80 xx 5 xx 10^(-3) xx 1.05(wt. V xx d) = 0.42 g`
`because w = (E.i.t)/(96500)`
`:. 0.42 = (108 xx 3 xx t)/(96500)`
`:. t = 125` sec.