Hydrated copper(II) ion, [Cu(H2O)4]^2+, in aqueous solution is:

NEET levelSingle correct optionDifficulty 1 of 3df121

Hydrated copper(II) ion, $[Cu (H X_{2} O) X_{4}] X^{2 +}$ , in aqueous solution is:

Cu X^{2 +}

3 d^{9}

. It has one unpaired electron, so it is paramagnetic, and a d-d transition makes it blue.