Q.63 Chemistry ⭐ 360° Option Elimination Active

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NEET 2025 Chemistry Question 63 Solution

Topic: Coordination Compounds · Official NTA Booklet Code 45

Question

Out of the following complex compounds, which of the compound will be having the minimum conductance in solution?

✓

Verified Against NTA Final Answer Key

Option (1) : [Co(NH₃)₃Cl₃] (OR [Co(NH₃)₄Cl₂]; both (1) and (2) awarded by NTA due to non-electrolyte formulation)

📚 Coordination Compounds Medium

📋 Given Parameters & Problem Setup

Option 1 Complex [Co(NH₃)₃Cl₃] (Neutral coordination sphere, 0 counter ions)

Option 2 Complex [Co(NH₃)₄Cl₂] (Printed as neutral coordination sphere, 0 counter ions)

Option 3 Complex [Co(NH₃)₆]Cl₃ (1:3 electrolyte, yields 4 ions)

Option 4 Complex [Co(NH₃)₅Cl]Cl (Printed as 1:1 electrolyte, yields 2 ions)

⚡

The 30-Second Exam Hall Shortcut: ⚡ Werner Ion Count and NTA Dual-Key Discovery

⏱️ Save ~40 seconds

Electrical conductance depends on the number of ions produced in solution! [Co(NH₃)₃Cl₃] is a non-electrolyte (0 ions ⟹ zero/minimum conductance). Option (2) was printed as [Co(NH₃)₄Cl₂] without counter-ion (also 0 ions)! NTA officially awarded full marks to BOTH (1) and (2)!

1 Werner’s theory: Only ions outside the coordination bracket [ ] ionize in aqueous solution.

2 Evaluate Option (1): [Co(NH₃)₃Cl₃] has all ligands inside the coordination sphere. It does not ionize in water (number of ions = 0) ⟹ NON-ELECTROLYTE with MINIMUM (zero) conductance!

3 Evaluate Option (2): Printed as [Co(NH₃)₄Cl₂]. Because there is no counter-ion outside the bracket, as written it also yields 0 ions in solution!

4 Evaluate Option (3): [Co(NH₃)₆]Cl₃ ionizes into [Co(NH₃)₆]³⁺ + 3 Cl⁻ (4 ions) ⟹ highest conductance.

5 Evaluate Option (4): [Co(NH₃)₅Cl]Cl ionizes into 2 ions.

6 Because both Option (1) and Option (2) yield zero ions based on printed formulas, NTA officially accepted both (1) and (2) (Key: A,B)!

🛡️

Why You Can 100% Trust This Shortcut: Werner’s Coordination Theory & Electrolytic Conductance (NCERT Chemistry · Coordination Compounds) & NTA Official Key.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Principle of Electrical Conductance in Coordination Compounds

The molar conductance of an aqueous solution of a coordination compound is directly proportional to the number of free ions produced per formula unit upon dissolution:

\text{Conductance} \propto \text{Total number of ions per formula unit}

• Ligands inside the coordination sphere [ ] are covalently/coordinatively bonded and do not dissociate in water.

Step 2

Analyze Ionization of Each Complex

Examine the ionization behavior of each given option:

[\text{Co(NH}_3)_3\text{Cl}_3] \xrightarrow{\text{H}_2\text{O}} \text{No ionization} \implies 0\text{ ions (Non-electrolyte)}

• Option (1): [Co(NH₃)₃Cl₃] is a neutral coordination complex with zero counter ions, giving essentially zero electrical conductance (minimum).
• Option (2): Printed as [Co(NH₃)₄Cl₂]. Without an external counter-ion, it represents a neutral entity yielding 0 ions in solution.
• Option (3): [Co(NH₃)₆]Cl₃ ⟶ [Co(NH₃)₆]³⁺ + 3 Cl⁻ (Total 4 ions) ⟹ Maximum conductance.
• Option (4): [Co(NH₃)₅Cl]Cl ⟶ [Co(NH₃)₅Cl]⁺ + Cl⁻ (Total 2 ions).

Step 3

NTA Official Multi-Key Verdict (A, B)

Standard textbook problems list [Co(NH₃)₄Cl₂]Cl (which yields 2 ions). However, the examination paper printed [Co(NH₃)₄Cl₂] with no external chlorine atom, making both (1) and (2) neutral non-electrolytes:

\text{Both [Co(NH}_3)_3\text{Cl}_3] \text{ and [Co(NH}_3)_4\text{Cl}_2] \text{ produce 0 ions} \implies \text{Key: A,B}

• NTA recognized this printing discrepancy and awarded full marks to candidates selecting either Option (1) or Option (2).

⭐

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 A

✓ 100% Correct

Verdict & Scientific Reason:

Officially accepted by NTA (A,B). Canonical neutral non-electrolyte producing 0 ions.

💡

Why this is airtight: None; awarded full marks.

2 B

✓ 100% Correct

Verdict & Scientific Reason:

Officially accepted by NTA (A,B). Printed as a neutral entity without counter-ion, yielding 0 ions.

💡

Why this is airtight: None; awarded full marks.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Produces 4 ions in solution, exhibiting the MAXIMUM conductance.

⚠️

Student Fallacy (Why candidates pick this trap): Selecting maximum conductance instead of minimum conductance.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Ionizes to give 2 ions, having significant conductance.

⚠️

Student Fallacy (Why candidates pick this trap): Thinking one counter-ion gives zero conductance.

⚠️

NTA Trap Alert: Maximum vs Minimum Conductance

Students frequently read "minimum conductance" and impulsively pick [Co(NH₃)₆]Cl₃ because it has the most chlorine atoms (3 Cl). But those 3 chlorines are outside the bracket and fully ionize to give MAXIMUM conductance!

🛡️ How to avoid the -1 mark: Remember: Inside bracket = NO ions = ZERO conductance (minimum)!

📖

Core NEET Syllabus Standard

NEET Chemistry Core Syllabus · Coordination Compounds Standard Benchmark

Core Scientific Principle Tested:

"Only primary valencies outside coordination sphere ionize; neutral complexes are non-electrolytes."

Syllabus Focus: Werner’s Theory & Electrolytic Behavior of Complexes

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

No outside ions = Non-electrolyte = Zero conductance (Key: A,B)!

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NEET 2025 Chemistry Question 63 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Werner Ion Count and NTA Dual-Key Discovery

Step-by-Step Rigorous Workflow & Mathematical Proof

Principle of Electrical Conductance in Coordination Compounds

Analyze Ionization of Each Complex

NTA Official Multi-Key Verdict (A, B)

360° Option Elimination Engine Key Feature

NTA Trap Alert: Maximum vs Minimum Conductance

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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