Question

Cerium (Z = 58) is an important member of the lanthanoids. Which of the following statements about cerium is incorrect?

• A. The common oxidation states of cerium are + 3 and + 4.
• B. The +3 oxidation state of cerium is more stable than +4 oxidation state.
• C. The + 4 oxidation state of cerium is not known in solutions.
• D. Cerium (IV) acts as an oxidising agent.

Answer 1

Answer: (C)

The + 4 oxidation state of cerium is not known in solutions.

$+4$ oxidation state of $Ce$ is known, it exhibits $+4$ oxidation state.

The outer electronic configuration is: $Xe4f^{1}5d^{1}6s^2$.

By losing $4e^{-}$ it acquires fully filled electronic configuration of Xenon $(2,8,18,18,8)$. As fully filled or half filled electronic configuration possesses extra-stability.