Which is not stable under ambient condition -

Options

A. `Fe^(3+)`
B. `Mn^(2+)`
C. `Ti^(4+)`
D. `Cu^(+)`

Answer

D

Explanation

Copper (I) compounds are unstable in aqueous solution and undergo disproportionation.
`2Cu^(+)rarr Cu^(2+)+Cu`
The greater stability of `Cu_((aq))^(2+)` than `Cu_((aq))^(+)` is due to much more `-ve Delta H_(hyd)` of `Cu_((aq))^(2+)` than `Cu_((aq))^(+)` which is compensates the second ionidation enthalpy of Cu.