Which element from following in +3 oxidation state forms colourless compounds?
Which element from following in +3 oxidation state forms colourless compounds?
Sc(Z=21)
Ti(Z=22)
V(Z=23)
$\mathrm{Fe}(Z=26)$
Solution
$\mathrm{Sc}^{3+} \Rightarrow 1 \mathrm{~s}^2 2 \mathrm{~s}^2 2 \mathrm{~s}^6 3 \mathrm{~s}^2 3 \mathrm{~s}^6 3 \mathrm{~d}^0$
$\mathrm{Sc}^{3+}$ ion will form colourless compounds as it does not contain unpaired electrons.