d and f Block Elements Part 2

(A) Cu (II) complexes are always paramagnetic as they have one unpaired electron due to d9 configuration of Cu(II)
(B) Cu(I) complexes are generally colourless due to d10 configuration.
(C) Cu(I) is easily oxidised to Cu+2 in aqueous solution 2Cu+→Cu+2+Cu
Cu+1 disproportionates to Cu+2 and Cu
( E‌cell ‌∘>0 for this cell reaction in aqueous solution)
In Fehling's solution, active reagent has Cu(II) which is reduced to Cu(I) on reaction with aldehydes.