`Cu^(+)` ion is not stable in aqueous solution because because of dispropotionation reaction. `E^(@)` value of disproportionation of `Cu^(+)` is
`[E_(Cu^(2+)//Cu^(+))^(@)=+ 0.15 V, E_(Cu^(2+)//Cu)^(@)=0.34 V]`

Options

A. second ionisation entyhalpy of copper is less than the first ionisation enthalpy
B. large value of second ionisation enthalpy of copper is compensated by much more negative hydration energy of `Cu_((aq))^(2+)`
C. hydration energy of `Cu_((aq))^(2+)` is much more negative than that of `Cu_((aq))^(2+)`
D. many copper (I) compounds are unstable in aqueous solution and undergo disproportionation rection.

Answer

B