Q.61 Chemistry ⭐ 360° Option Elimination Active

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NEET 2023 Chemistry Question 61 Solution

Topic: Coordination Compounds · Official NTA Booklet Code G5

Question

Homoleptic complex from the following complexes is:

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Verified Against NTA Final Answer Key

Option (2) : Potassium trioxalatoaluminate (III)

📚 Coordination Compounds Easy

📋 Given Parameters & Problem Setup

Target classification Homoleptic complex

Definition Central metal atom/ion bound to only ONE type of donor group/ligand

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The 30-Second Exam Hall Shortcut: ⚡ Prefix & Ligand Variety Scan: Homo = ONE Ligand Type

⏱️ Save ~30 seconds

Potassium trioxalatoaluminate (III) is K₃[Al(C₂O₄)₃], containing ONLY oxalate ligands! All other options contain two or three different ligand types (heteroleptic). Option (2) in 5 seconds!

1 Homoleptic complex: A coordination entity where the metal is bound to only ONE kind of ligand.

2 Heteroleptic complex: A coordination entity where the metal is bound to more than one kind of ligand.

3 Option (1): Triamminetriaquachromium (III) chloride contains NH₃ AND H₂O (two ligand kinds ⟹ Heteroleptic).

4 Option (2): Potassium trioxalatoaluminate (III) contains ONLY oxalate (ox²⁻) ligands ⟹ HOMOLEPTIC.

5 Option (3): Diamminechloridonitrito-N-platinum (II) contains NH₃, Cl⁻, and NO₂⁻ (three ligand kinds ⟹ Heteroleptic).

6 Option (4): Pentaamminecarbonatocobalt (III) chloride contains NH₃ AND CO₃²⁻ (two ligand kinds ⟹ Heteroleptic).

7 Select Option (2) directly!

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Why You Can 100% Trust This Shortcut: Coordination Chemistry · IUPAC Terminology (Complexes in which a metal is bound to only one kind of donor groups are homoleptic, e.g., [Al(C₂O₄)₃]³⁻).

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Definition of Homoleptic Coordination Entities

According to IUPAC coordination chemistry conventions, complexes are classified based on the diversity of their coordinating donor ligands: (i) Homoleptic complexes: complexes in which the central metal atom or ion is coordinated to only ONE type of ligand species; (ii) Heteroleptic complexes: complexes in which the metal ion is coordinated to two or more chemically distinct types of ligands.

\text{Homoleptic: } [\text{M}(\text{L})_n]^{m\pm}, \qquad \text{Heteroleptic: } [\text{M}(\text{L}_1)_a(\text{L}_2)_b]^{m\pm}

Step 2

Chemical Formula of Option 2

Potassium trioxalatoaluminate (III) has the chemical formula K₃[Al(C₂O₄)₃]. In this complex, the central aluminum(III) ion is coordinated exclusively to three bidentate oxalate ligands (C₂O₄²⁻):

\text{K}_3[\text{Al}(\text{C}_2\text{O}_4)_3] \implies \text{Coordination sphere contains only oxalate ligands } (\text{Homoleptic})

Step 3

Formulas and Analysis of Heteroleptic Distractors

Writing the coordination formulas for the remaining choices reveals multiple distinct ligand types:

\begin{aligned} \text{Option 1: } &[\text{Cr}(\text{NH}_3)_3(\text{H}_2\text{O})_3]\text{Cl}_3 \quad (\text{Ligands: } \text{NH}_3, \text{H}_2\text{O} \implies \text{Heteroleptic}) \\[4pt] \text{Option 3: } &[\text{Pt}(\text{NH}_3)_2\text{Cl}(\text{NO}_2)] \quad (\text{Ligands: } \text{NH}_3, \text{Cl}^-, \text{NO}_2^- \implies \text{Heteroleptic}) \\[4pt] \text{Option 4: } &[\text{Co}(\text{NH}_3)_5(\text{CO}_3)]\text{Cl} \quad (\text{Ligands: } \text{NH}_3, \text{CO}_3^{2-} \implies \text{Heteroleptic}) \end{aligned}

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360° Option Elimination Engine Key Feature

Diagnose every choice: Know exactly why the right option works and why distractors fail.

4-Option Deep Scan

1 (1)

✗ Incorrect

Verdict & Scientific Reason:

Heteroleptic: contains both ammine (NH₃) and aqua (H₂O) ligands.

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Student Fallacy (Why candidates pick this trap): Candidate saw identical stoichiometric counts (3 and 3) and guessed homoleptic.

2 (2)

✓ 100% Correct

Verdict & Scientific Reason:

Accurate homoleptic complex: contains exclusively oxalate ligands [Al(C₂O₄)₃]³⁻.

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Why this is airtight: None. Candidate correctly verified single ligand type.

3 (3)

✗ Incorrect

Verdict & Scientific Reason:

Heteroleptic: contains three distinct ligand types (ammine, chlorido, nitrito-N).

⚠️

Student Fallacy (Why candidates pick this trap): Candidate overlooked the presence of multiple ligands.

4 (4)

✗ Incorrect

Verdict & Scientific Reason:

Heteroleptic: contains ammine and carbonato ligands.

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Student Fallacy (Why candidates pick this trap): Candidate saw pentaammine (5 ammines) and ignored the carbonato ligand.

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NTA Trap Alert: Confusing Counter Ions with Coordination Ligands

Potassium (K⁺) in K₃[Al(C₂O₄)₃] is an ion outside the coordination bracket. Only the species INSIDE the coordination square brackets define homoleptic vs heteroleptic character.

🛡️ How to avoid the -1 mark: Focus strictly inside the brackets: If there is only ONE type of ligand inside [ ], it is homoleptic.

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Core NEET Syllabus Standard

National Eligibility cum Entrance Test (NEET UG) · Coordination Compounds Standard Benchmark

Core Scientific Principle Tested:

"Homoleptic complexes have central metal bound to only one kind of donor groups; heteroleptic complexes have more than one kind."

Syllabus Focus: Definitions of Some Important Terms Pertaining to Coordination Compounds

Preserved in Rationalized Curriculum Syllabus & Academic Standards ↗

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NEET 2023 Chemistry Question 61 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Prefix & Ligand Variety Scan: Homo = ONE Ligand Type

Step-by-Step Rigorous Workflow & Mathematical Proof

Definition of Homoleptic Coordination Entities

Chemical Formula of Option 2

Formulas and Analysis of Heteroleptic Distractors

360° Option Elimination Engine Key Feature

NTA Trap Alert: Confusing Counter Ions with Coordination Ligands

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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