Question

Assertion (A) Many trivalent lanthanoid ions are coloured both in solid state and in aqueous solution.
Reason (R) Colour of these ions is due to the presence of $f$-electrons.

• A. Both $A$ and $R$ are correct; $R$ is the correct explanation of $A$.
• B. Both $A$ and $R$ are correct; $R$ is not the correct explanation of $A$.
• C. $A$ is correct; $R$ is incorrect.
• D. $R$ is correct; $A$ is incorrect.

Answer 1

Answer: (A)

Many trivalent lanthanoid ions are coloured due to the presence of unpaired $f$-electrons, in solid state as well as in aqueous solutions.