Q46 / 180 · COMEDK 2020 · Chemistry

Which of the following forms a colourless solution in aqueous medium? @@

  • A
    $\mathrm{Ti}^{3+}$
  • Correct answer
    B
    $\mathrm{Sc}^{3+}$
  • C
    $\mathrm{V}^{3+}$
  • D
    $\mathrm{Cr}^{3+}$

Solution

The electronic configuration of $\mathrm{Sc}$ is $1 s^{8} 2 s^{8} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{1} 4 s^{2}$ Electronic configuration of Sc ${ }^{3+}$ is $1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6}$. $\mathrm{So}, \mathrm{Sc}^{3+}$ is colourless due to the absence of unpuired electrons in $d$-orbital.

Hence, the correct answer is option: 'B'.

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