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# In an electrolysis experiment electric current was passed for 5hr through two cells connected in series.The first cell contains gold salt and second contains $CuSO_4$ solution.9.83g of gold was deposited in first cell.If the oxidation number of Au is +3,find the amount of copper deposited in second cell

$\begin{array}{1 1}(a)\;4g&(b)\;5g\\(c)\;4.7g&(d)\;5.7g\end{array}$

At weight of gold is 197.
Eq.wt of gold =$\large\frac{At.wt}{\text{Oxidation number}}=\frac{197}{3}$
$\Rightarrow 65.66$
As we know that
$\large\frac{W_{Au}}{W_{Cu}}=\frac{E_{Au}}{E_{Cu}}$
$\large\frac{9.83}{W_{Cu}}=\frac{65.66}{63.5/2}$
$W_{Cu}=4.7g$
Hence (c) is the correct answer.