Which of the following pairs has both the ions coloured in aqueous solution? [Atomic numbers of $\mathrm{Sc}=21, \mathrm{Ti}=22, \mathrm{Ni}=28, \mathrm{Cu}=29, \mathrm{Mn}=25$ ]

• A

  $\mathrm{Sc}^{3+}, \mathrm{Mn}^{2+}$
• B

  $\mathrm{Ni}^{2+}, \mathrm{Ti}^{4+}$
• C

  $\mathrm{Ti}^{3+}, \mathrm{Cu}^{+}$
• Correct answer
  D

  $\mathrm{Mn}^{2+}, \mathrm{Ti}^{3+}$

Solution

$\therefore$ Only option (d) (i.e. $\mathrm{Mn}^{2+}, \mathrm{Ti}^{3+}$ pair) is coloured in aqueous solution.

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