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Give reasons for the following.
The complex ion is coloured. (Atomic number of )
The complex ion $[\text{Ti}(\text{H}_2\text{O})_6]^{3+}$ is coloured.
(Atomic number of $\text{Ti} = 22$)
Answer
Answer
AI$\mathrm{Ti^{3+}}$ has the configuration $3d^1$. In the octahedral field of water the d-orbitals split into $t_{2g}$ and $e_g$; the single electron in $t_{2g}$ absorbs visible light (d-d transition) and jumps to $e_g$, so the complex shows the complementary colour (purple).
From ISC 2026 Improvement Chemistry Paper 1, question 6(ii).