question_answer

\[Z{{n}^{2+}}\] salts are white while \[C{{u}^{2+}}\] salts are blue.

Answer:

                  \[C{{u}^{2+}}\] ion \[(3{{d}^{9}})\] has one half filled d-orbital. Therefore, it has an urge to take part in                d?d transition. The compounds containing \[C{{u}^{2+}}\] ion (e.g., \[CuS{{O}_{4}}.5{{H}_{2}}O\]) are coloured. \[Z{{n}^{2+}}\] ion \[(3{{d}^{10}})\] has completely filled d-orbitals and there is no scope for any electron transition. Therefore, \[Z{{n}^{2+}}\] salts are white and not coloured.