Q.87 Chemistry ⭐ 360° Option Elimination Active
NEET 2026 Chemistry Question 87 Solution
Topic: Coordination Compounds & Solutions · Official NTA Booklet Code 50
Question
A 1:3 electrolyte in an aqueous solution is
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Verified Against NTA Final Answer Key
Option (3) : [Co(NH₃)₆]Cl₃
📚 Coordination Compounds & Solutions Easy
📋 Given Parameters & Problem Setup
Requirement A 1:3 electrolyte in an aqueous solution
Options [CoCl₂(NH₃)₄]Cl, [CoCl(NH₃)₅]Cl₂, [Co(NH₃)₆]Cl₃, [Co(NH₃)₃(NO₂)₃]
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⏱️ Save ~40 seconds The 30-Second Exam Hall Shortcut: ⚡ Count Cation vs Anion Ion Ratio
A 1:3 electrolyte produces 1 complex cation and 3 simple anions!
1 [CoCl₂(NH₃)₄]Cl → [CoCl₂(NH₃)₄]⁺ + 1 Cl⁻ (1:1 electrolyte).
2 [CoCl(NH₃)₅]Cl₂ → [CoCl(NH₃)₅]²⁺ + 2 Cl⁻ (1:2 electrolyte).
3 [Co(NH₃)₆]Cl₃ → [Co(NH₃)₆]³⁺ + 3 Cl⁻ (1:3 ELECTROLYTE!).
4 [Co(NH₃)₃(NO₂)₃] → Neutral complex, does not ionize (non-electrolyte).
5 Option (3) is instantly spotted in 5 seconds!
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Why You Can 100% Trust This Shortcut: Werner's coordination theory: Ionizable counter-ions exist outside the square bracket, while non-ionizable ligands reside inside.
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Step-by-Step Rigorous Workflow & Mathematical Proof
Step 1
Define 1:3 Electrolyte
An electrolyte of type 1:3 (or A B₃) dissociates in aqueous solution to yield one cation and three anions (total of 4 ions per formula unit).
- • Produces 1 cation and 3 anions.
Step 2
Examine the Dissociation of Each Option
1. [CoCl₂(NH₃)₄]Cl: [CoCl₂(NH₃)₄]Cl → [CoCl₂(NH₃)₄]⁺ + Cl⁻ (1 cation + 1 anion = 1:1 electrolyte, total 2 ions). 2. [CoCl(NH₃)₅]Cl₂: [CoCl(NH₃)₅]Cl₂ → [CoCl(NH₃)₅]²⁺ + 2 Cl⁻ (1 cation + 2 anions = 1:2 electrolyte, total 3 ions). 3. [Co(NH₃)₆]Cl₃: [Co(NH₃)₆]Cl₃ → [Co(NH₃)₆]³⁺ + 3 Cl⁻ (1 cation + 3 anions = 1:3 electrolyte, total 4 ions). 4. [Co(NH₃)₃(NO₂)₃]: Neutral coordination compound, does not dissociate (non-electrolyte, 0 ions).
- • Option (3) is a 1:3 electrolyte.
Step 3
Conclusion
[Co(NH₃)₆]Cl₃ is a 1:3 electrolyte.
- • Matches Option (3).
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4-Option Deep Scan
360° Option Elimination Engine Key Feature
Diagnose every choice: Know exactly why the right option works and why distractors fail.
1 A
✗ Incorrect Verdict & Scientific Reason:
Incorrect. Produces only one Cl⁻ ion in solution, making it a 1:1 electrolyte.
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Student Fallacy (Why candidates pick this trap): Counting the two chlorido ligands inside the coordination sphere.
2 B
✗ Incorrect Verdict & Scientific Reason:
Incorrect. Produces two Cl⁻ counter-ions, making it a 1:2 electrolyte.
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Student Fallacy (Why candidates pick this trap): Miscounting the outer chloride subscript.
3 C
✓ 100% Correct Verdict & Scientific Reason:
Exact: Dissociates into one [Co(NH₃)₆]³⁺ cation and three Cl⁻ anions (1:3 electrolyte).
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Why this is airtight: None; standard Werner coordination dissociation.
4 D
✗ Incorrect Verdict & Scientific Reason:
Incorrect. Non-ionic coordination entity with zero ionizable counter-ions.
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Student Fallacy (Why candidates pick this trap): Assuming coordination compounds always dissociate into ions.
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NTA Trap Alert: Counting Chlorido Ligands Inside the Square Bracket
Ligands inside the square bracket [ ... ] are covalently/coordinatively bonded to the transition metal and do NOT ionize in water. Only ions OUTSIDE the bracket dissociate!
🛡️ How to avoid the -1 mark: Only look at what is outside the bracket: Cl₃ outside means 3 chloride ions are formed.
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Core NEET Syllabus Standard
NEET Chemistry Core Syllabus · Coordination Compounds Standard Benchmark
Core Scientific Principle Tested:
"Primary valencies (outside the sphere) ionize; secondary valencies (inside the sphere) do not."
Syllabus Focus: Werner's theory of coordination compounds and electrical conductance
✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗
Three chlorides outside the gate: 1:3 electrolyte is its fate!
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