The Question is from neet-chemistry , and it was created by the author THIRUPATHI REDDY

Question

Of the ions ${\rm{Z}}{{\rm{n}}^{2 + }},{\rm{\;N}}{{\rm{i}}^{2 + }}$ and ${\rm{C}}{{\rm{r}}^{3 + }}$, (atomic number of Zn=30, Ni=28, Cr=24)

THIRUPATHI REDDY · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Transition metal ion color
 **Related Topics**: d-orbital electronic configuration, crystal field theory
 **Prerequisites**: Understanding of electronic configurations, and the relationship between electronic transitions and color.
## SOLUTION PATHWAY
**Given Information**:
  Ions: $Zn^{2+}$, $Ni^{2+}$, $Cr^{3+}$
  Atomic numbers: Zn = 30, Ni = 28, Cr = 24
**Method & Steps**:
 1. Determine the electronic configurations of the ions.
  $Zn^{2+}$: $[Ar]3d^{10}$ (completely filled d-orbital)
  $Ni^{2+}$: $[Ar]3d^{8}$ (partially filled d-orbital)
  $Cr^{3+}$: $[Ar]3d^{3}$ (partially filled d-orbital)
 2. Relate electronic configuration to color.
  Transition metal ions exhibit color due to d-d electronic transitions.  These transitions occur when an electron absorbs energy and moves from a lower energy d-orbital to a higher energy d-orbital.  This is only possible if there are partially filled d-orbitals.
  A completely filled or empty d-orbital ($Zn^{2+}$) prevents d-d transitions, resulting in a colorless ion.
  Partially filled d-orbitals ($Ni^{2+}$ and $Cr^{3+}$) allow for d-d transitions and thus, color.
 3. Determine the color of each ion.
  $Zn^{2+}$: Colorless
  $Ni^{2+}$: Colored (green or blue, depending on the ligand)
  $Cr^{3+}$: Colored (various shades depending on the ligand)
  Result: Only $Zn^{2+}$ is colorless, while $Ni^{2+}$ and $Cr^{3+}$ are colored.
  Verification: This aligns with the observed properties of these ions.
 ## OPTION ANALYSIS
A :x: Incorrect.  $Zn^{2+}$ is colorless.
B :x: Incorrect. $Ni^{2+}$ and $Cr^{3+}$ are colored.
C ✓: Correct.  Only $Zn^{2+}$ is colorless, and $Ni^{2+}$ and $Cr^{3+}$ are colored.
D :x: Incorrect. $Cr^{3+}$ is colored.
 ## LEARNING AIDS
 **Common Mistakes**:
  1. Assuming all transition metal ions are colored: Remember that a completely filled d-orbital prevents d-d transitions.
  2. Incorrectly assigning colors to ions without considering the ligand environment: The exact color depends on the ligands surrounding the metal ion.
 **Quick Tips**:
  1. Check the d-electron configuration:  A completely filled or empty d-orbital indicates a colorless ion.
  2. Remember that the presence of partially filled d orbitals is necessary but not sufficient to guarantee color. The energy difference between orbitals must also be within the visible light spectrum.

THIRUPATHI REDDY · Answer

All three are coloured

THIRUPATHI REDDY · Answer

All three are colourless

THIRUPATHI REDDY · Answer

The correct Option is "Only ${\rm{Z}}{{\rm{n}}^{2 + }}$ is colourless and ${\rm{N}}{{\rm{i}}^{2 + }}$ and ${\rm{C}}{{\rm{r}}^{3 + }}$ are coloured"

THIRUPATHI REDDY · Answer

Only ${\rm{N}}{{\rm{i}}^{2 + }}$ is coloured and ${\rm{Z}}{{\rm{n}}^{2 + }}$ and ${\rm{C}}{{\rm{r}}^{3 + }}$ are colourless

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