In the electrolysis of copper(II) chloride solution, the mass of cathode is increased by $3 .15 g$. At copper anode, we will have

Since anode is copper, the reaction occurring here is $\mathrm{Cu}\to {\mathrm{Cu}}^{2+}+2{\mathrm{e}}^{-}$

Thus, there will occur a loss of Cu at anode which will also equal to 3 .15 g.

In the electrolysis of copper(II) chloride solution, the mass of cathode is increased by $3.15 g$. At copper anode, we will have the loss of 3.15 g of $\mathrm{Cu}$