A thin strip of iron with a mass of 15.5g is placed into a solution containing 21.0g of copper (II) sulfate and copper begins to form. After some times, the reactions stops because all the copper (II) sulfate has reacted. The iron strip is found to have a mass of 8.5g. The mass of copper formed is found to be 8.60g. What mass of iron (II) sulfate has been formed in the reaction?

Question

$\begin{array}{1 1} (a)\; 19.40\; g \\ (b)\; 12.45 \;g \\ (c)\; 15.78\; g \\ (d)\; 22.40\; g \end{array} $