JAMB Physics 2014 Paper

Concept:Electrolysis follows Faraday’s law: the mass of a substance deposited is directly proportional to the charge that passes through the electrolyte.Explanation:The relevant formula is $m = ZIt$, where $m$ is the mass deposited, $Z$ is the electrochemical equivalent, $I$ is the current, and $t$ is the time in seconds.Convert the time from hours to seconds:$t = 2 \text{ hours} = 2 \times 60 \times 60 = 7200 \text{ s}$.Substitute the given values:$Z = 3.3 \times 10^{-7} \text{ kgC}^{-1}$, $I = 4 \text{ A}$, $t = 7200 \text{ s}$.$m = (3.3 \times 10^{-7}) \times 4 \times 7200$$m = 9.504 \times 10^{-3} \text{ kg}$$m \approx 9.5 \times 10^{-3} \text{ kg}$.This matches the option showing $9.5 \times 10^{-3} \text{ kg}$.Answer:The mass of copper deposited is $9.5 \times 10^{-3} \text{ kg}$, which is option C.