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Question

Chemistry Question on The Lanthanoids

The purple colour of KMnO4{KMnO4} is due to the transition

A

C.T.(LM)C.T. (L \to M)

B

C.T.(ML)C.T. (M \to L)

C

ddd-d

D

pdp-d

Answer

C.T.(LM)C.T. (L \to M)

Explanation

Solution

The permanganate ion has an intense purple colour. Mn (+ VII) has a d0d^0 configuration. So the colour arises from charge transfer and not from d?d spectra.
In MnO4{MnO4^{-}} an electron is momentarily changing O{O^{- -}} to O{O^{-}} and reducing the oxidation state of the metal from Mn(VII) to Mn (VI). Charge transfer requires that the energy levels on the two different atoms are fairly close.
O=(8)=2K,6LO = (8) = 2_K , 6_L
Mn(25)=2K,8L,15MMn (25) = 2_K , 8_L , 15_M
hence the charge transfer occurs from LML \to M