Out of $Cu_2Cl_2$ and $CuCl_2$,which is more stable and why?

(B) $CuCl_2$ is more stable in an aqueous solution than $Cu_2Cl_2$.
This is because the high hydration enthalpy of $Cu^{2+}(aq)$ compensates for the high second ionization enthalpy required to convert $Cu^+(g)$ to $Cu^{2+}(g)$.
Although the first ionization enthalpy of $Cu$ is lower than the second,the hydration energy released when $Cu^{2+}$ ions are formed in water is significantly higher than that of $Cu^+$ ions,making $Cu^{2+}$ salts more stable in aqueous media.