Question

Which of the following is a correct statement?

• A. Aqueous solutions of $C{u}^{+}$ and $Z{n}^{2+}$ are colourless
• B. Aqueous solutions of $C{u}^{2+}$ and $Z{n}^{2+}$ are colourless
• C. Aqueous solution of $F{e}^{3+}$ is green in colour
• D. Aqueous solution of $Mn{O}_4^{-}$ is colourless

Answer 1

Answer: (A)

(a) $C{u}^{+}=[Ar]3d^{10}$

(No unpaired electrons, so it is colourless)
$Z{n}^{2+}=[Ar]3d^{10}$
(No unpaired electrons, so it is colourless)
(b) $C{u}^{2+}=[Ar]3d^9$

(One unpaired electron is present, so it is coloured)
$Z{n}^{2+}$ is colourless.
(c) The colour of $F{e}^{2+}$ is green while that of $F{e}^{3+}$ is blue.
(d) $Mn{O}_4^{-}$ contains no unpaired electrons, however, it is coloured due to charge transfer.