Cadmium Is a Toxic Heavy Metal If the Silver Ion Concentration Were 1

Cadmium is a toxic heavy metal. The U.S. Environmental Protection Agency limits the concentration of cadmium ions in drinking water to less than 4 * 10^-8 M. Assess the feasibility of monitoring of cadmium in drinking water using a voltaic cell based on the following half-reactions. $$\begin{aligned}\mathrm { Ag } ^ { + } ( a q ) + \mathrm { e } ^ { - } \longrightarrow \mathrm { Ag } ( s ) & E ^ { \circ } = + 0.7996 \mathrm {~V} \\\mathrm { Cd } ^ { 2 + } ( a q ) + 2 \mathrm { e } ^ { - } \longrightarrow \mathrm { Cd } ( s ) & E ^ { \circ } = - 0.4030 \mathrm {~V}\end{aligned}$$ If the silver ion concentration were 1.000 M, what cadmium ion concentration at 298 K would increase the cell potential by 10 mV from the standard cell potential?

A) 0.36 M
B) 4.6 M
C) 0.46 M
D) 0.68 M
E) 6.8 M