Question

Which of the following ions will exhibit colour in aqueous solution ?

• A. $L{u}^{3+}\left(Z=71\right)$
• B. $S{c}^{3+}\left(Z=21\right)$
• C. $L{a}^{3+}\left(Z=57\right)$
• D. $T{i}^{3+}\left(Z=22\right)$

Answer 1

Answer: (D)

$L{u}^{3+}=4f^{14}$ Colourless
$S{c}^{3+}=3d^0$ Colourless
$L{a}^{3+}=4f^0$ Colourless
$T{i}^{3+}=3d^1$ Coloured (purple)
Transition metal ions and inner transition metal ions having $d^1$ to $d^9$ configuration and $f^1$ to $f^{13}$ configuration are coloured due to $d-d$ transition and $f-f$ transition respectively. Ions having $d^0$ and $d^{10}$ or $f^0$ and $f^{14}$ configuration are colourless.