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. 124 sec
C. 135 sec
D. 145 sec

Answer

B

Explanation

Weight of Ag required = `V xx d`
`= 80 xx 5 xx 10^(-3) xx 1.05 = 0.42`
`because W = ("Eit")/(96500) `
`therefore 0.42 = (108 xx 3 xx t)/(96500) implies t = 125` sec .