Question

The correct set of ions (aqueous solution) with the same colour from the following is:

• A. \( V^{2+} \), \( Cr^{3+} \), \( Mn^{3+} \)
• B. \( Zn^{2+} \), \( V^{3+} \), \( Fe^{3+} \)
• C. \( Ti^{4+} \), \( V^{4+} \), \( Mn^{2+} \)
• D. \( Sc^{3+} \), \( Ti^{3+} \), \( Cr^{2+} \)

Hint:

The colour of transition metal ions in aqueous solutions is determined by the d-electron configuration and the ligand field around the ion. Ions that are part of the same group or period often exhibit similar colours due to similar electronic transitions.

Answer 1

The Correct Option is A

To identify aqueous ions with matching colors, we examine the characteristic colors of transition metal ions, which arise from d-d electron transitions. The colors of the ions in each provided option are analyzed:

1. \(V^{2+}\), \(Cr^{3+}\), \(Mn^{3+}\):
   • \(V^{2+}\): Pale violet or lavender.
   • \(Cr^{3+}\): Predominantly green in aqueous solutions, but can also be violet depending on ligands.
   • \(Mn^{3+}\): Frequently pale purple.
2. \(Zn^{2+}\), \(V^{3+}\), \(Fe^{3+}\):
   • \(Zn^{2+}\): Colorless (not a transition metal).
   • \(V^{3+}\): Typically green.
   • \(Fe^{3+}\): Usually yellow or brown in water.
3. \(Ti^{4+}\), \(V^{4+}\), \(Mn^{2+}\):
   • \(Ti^{4+}\): Colorless (not a transition metal).
   • \(V^{4+}\): Typically blue.
   • \(Mn^{2+}\): Pale pink.
4. \(Sc^{3+}\), \(Ti^{3+}\), \(Cr^{2+}\):
   • \(Sc^{3+}\): Colorless.
   • \(Ti^{3+}\): Purple.
   • \(Cr^{2+}\): Blue.

Based on this analysis, the first option is correct, as \(V^{2+}\), \(Cr^{3+}\), and \(Mn^{3+}\) can exhibit similar shades of violet and purple. The identified set is:

\(V^{2+}\), \(Cr^{3+}\), \(Mn^{3+}\)