Knowing that the chemistry of lanthanoids (Ln) is dominated by its +3 oxidation state, which of the following statements is incorrect? a)Because of the large size of the Ln(III) ions, the bonding in its compounds is predominantly ionic in character. b)The ionic sizes of Ln (III) decrease in general with increasing atomic number. c)Ln(III) compounds are generally colourless. d)Ln(III) hydroxides are mainly basic in character..

Options

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

Answer

C

Explanation

A) Lanthanoid (III)ions form ionic compounds due to their large size:
B) The decrease in size of atoms and ions with increase in atomic number is known as lanthanoid contraction,
C) Most.lanthanoids are silvery white metals and most of trivalent metal ions are coloured due to partially filled f-orbitals which permits f-f transition
D) Lanthanoids form hydroxides of the type `M(OH)_3`, which are basic in nature.