Question

$Ti ^{2+}$ is purple while $Ti ^{4+}$ is colourless, because

• A. there is no crystal field effect in $Ti ^{4+}$
• B. $Ti ^{2+}$ has $3 d^{2}$ configuration
• C. $Ti ^{4+}$ has $3 d^{2}$ configuration
• D. $Ti ^{4+}$ is a very small cation when compared to $Ti ^{2+}$ and hence, does not absorb any radiation.

Answer 1

Answer: (B)

$ T i(22) \rightarrow 3 d^{2} 4 s^{2}$

$Ti ^{2+} \rightarrow 3 d^{2} 4 s^{0}(d-d$ transition is possible, so it is coloured)

$Ti ^{4+} \rightarrow 3 d^{0} 4 s^{0}$ (no $d-d$ transition, colourless)