Question

Knowing that the chemistry of lanthanoids (Ln) is dominated by its +3 oxidation state, which of the following statements is incorrect?

• A. The ionic size of Ln(III) decreases in general with increasing atomic number
• B. Ln(III) compounds are generally colourless
• C. Ln(III) hydroxides are mainly basic in character
• D. Because of the large size of Ln(III) ions, the bonding in its compounds is predominantly ionic in character

Hint:

f–f electronic transitions are responsible for colours in lanthanoids.

Answer 1

The Correct Option is B

Step 1: Lanthanoid contraction causes decrease in ionic size.
Step 2: Ln(III) compounds are generally coloured due to f–f transitions.
Step 3: Hence statement (B) is incorrect.