JEE Chemistry 2025 Question with Solution

Given: We need to identify the set of transition metal ions in aqueous solution that have the same colour.

Find: The correct option among A, B, C, and D.

The colour of transition metal ions in aqueous solution depends on d-d transitions, which are governed by the d-electron configuration and the ligand field around the ion.

Now compare the ions in each set:

1. Option A: $V^{2+}$, $Cr^{3+}$, $Mn^{3+}$

• $V^{2+}$: pale violet or lavender
• $Cr^{3+}$: green in many aqueous solutions, but can also appear violet depending on the ligands present
• $Mn^{3+}$: pale purple

These ions can appear in similar violet or purple shades.

2. Option B: $Zn^{2+}$, $V^{3+}$, $Fe^{3+}$

• $Zn^{2+}$: colourless
• $V^{3+}$: green
• $Fe^{3+}$: yellow or brown

These do not have the same colour.

3. Option C: $Ti^{4+}$, $V^{4+}$, $Mn^{2+}$

• $Ti^{4+}$: colourless
• $V^{4+}$: blue
• $Mn^{2+}$: pale pink

These do not have the same colour.

4. Option D: $Sc^{3+}$, $Ti^{3+}$, $Cr^{2+}$

• $Sc^{3+}$: colourless
• $Ti^{3+}$: purple
• $Cr^{2+}$: blue

These do not have the same colour.

Therefore, the set of ions with the same colour is $V^{2+}$, $Cr^{3+}$, and $Mn^{3+}$.

The correct option is A.

Given: Transition metal ions in aqueous solution show characteristic colours due to electronic transitions.

Find: Which listed set shows similar colour in aqueous solution.

A useful comparison is:

• Ions with no d-electrons or completely filled d-orbitals are often colourless.
• Ions with partially filled d-orbitals may show visible colour due to d-d transitions.

Checking the sets:

• $Zn^{2+}$ and $Ti^{4+}$ are colourless, so B and C cannot be correct.
• $Sc^{3+}$ is also colourless, so D cannot be correct.
• In A, the ions $V^{2+}$, $Cr^{3+}$, and $Mn^{3+}$ are described in the solution as showing similar violet or purple shades.

Hence, A is the only defensible choice.

Therefore, the correct option is A.