Q.54 Chemistry ⭐ 360° Option Elimination Active
NEET 2023 Chemistry Question 54 Solution
Topic: Surface Chemistry · Official NTA Booklet Code G5
Question
Which one is an example of heterogenous catalysis?
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Verified Against NTA Final Answer Key
Option (1) : Combination between dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron.
📚 Surface Chemistry Easy
📋 Given Parameters & Problem Setup
Criterion Heterogeneous catalysis (Reactants and catalyst in different physical phases)
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⏱️ Save ~30 seconds The 30-Second Exam Hall Shortcut: ⚡ Phase Comparison Hack: Reactants (Gas) vs Catalyst (Solid)
Haber process: N₂(g) + H₂(g) over solid Fe(s) ⟹ Gaseous reactants on a solid catalyst = Heterogeneous Catalysis in 5 seconds! (All other options have identical phases).
1 Heterogeneous catalysis definition: The catalyst exists in a physical phase DIFFERENT from the reactants.
2 Examine Option (1) Haber process: N₂(g) + 3H₂(g) ⟶ 2NH₃(g) with solid iron Fe(s). Reactants are gaseous, catalyst is solid ⟹ HETEROGENEOUS.
3 Examine Option (2) Lead chamber process: SO₂(g) + O₂(g) catalyzed by NO(g). All gases ⟹ HOMOGENEOUS.
4 Examine Option (3) Inversion of cane sugar: Sucrose(aq) + H₂O(l) catalyzed by H⁺(aq). All liquid/aqueous ⟹ HOMOGENEOUS.
5 Examine Option (4) Ozone depletion: O₃(g) catalyzed by NO(g). All gases ⟹ HOMOGENEOUS.
6 Select Option (1) immediately!
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Why You Can 100% Trust This Shortcut: Surface Chemistry · Classification of Catalysis (Heterogeneous catalysis is characterized by phase boundary between reactants and catalyst, typically gas/solid or liquid/solid adsorption).
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Step-by-Step Rigorous Workflow & Mathematical Proof
Step 1
Definition of Heterogeneous Catalysis
When the catalyst and the reactants are in different phases, the catalytic process is termed heterogeneous catalysis. The reaction typically proceeds via the adsorption theory at the solid catalyst’s active surface sites:
Step 2
Phase Analysis of Option 1 (Haber Process)
In the industrial synthesis of ammonia by Haber’s process, dinitrogen gas and dihydrogen gas react over solid finely divided iron containing molybdenum or potassium oxide promoter:
Step 3
Confirmation of Phase Difference
The reactants (N₂ and H₂) are in the gaseous phase, whereas the catalyst (Fe) is in the solid phase. Because the phases are different, this is a classic canonical example of heterogeneous catalysis.
Step 4
Phase Analysis of Distractors (Homogeneous Reactions)
In all other options, reactants and catalysts share the identical phase:
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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 (1)
✓ 100% Correct Verdict & Scientific Reason:
Accurate: Reactants are gaseous (N₂, H₂) and catalyst is solid (Fe) — distinct physical phases.
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Why this is airtight: None. Candidate correctly identified the phase boundary.
2 (2)
✗ Incorrect Verdict & Scientific Reason:
Homogeneous catalysis: SO₂, O₂, and NO are all in the gaseous phase.
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Student Fallacy (Why candidates pick this trap): Candidate forgot that NO catalyst is a gas in the lead chamber process.
3 (3)
✗ Incorrect Verdict & Scientific Reason:
Homogeneous catalysis: Sugar, water, and acid catalyst H⁺ are all in the liquid/aqueous phase.
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Student Fallacy (Why candidates pick this trap): Candidate thought dissolved solid sugar made it heterogeneous.
4 (4)
✗ Incorrect Verdict & Scientific Reason:
Homogeneous catalysis: Ozone and NO are both gases.
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Student Fallacy (Why candidates pick this trap): Candidate overlooked the uniform gaseous phase.
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NTA Trap Alert: Confusing Sugar Hydrolysis with Heterogeneous Catalysis
Because sugar starts as solid crystalline table sugar, students often mistakenly classify sugar hydrolysis as heterogeneous. However, the reaction occurs in AQUEOUS SOLUTION, meaning reactants and H⁺ ions are in the same liquid phase (homogeneous).
🛡️ How to avoid the -1 mark: Check the reaction medium: Once dissolved, solutions are single-phase liquid systems.
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Core NEET Syllabus Standard
National Eligibility cum Entrance Test (NEET UG) · Surface Chemistry Standard Benchmark
Core Scientific Principle Tested:
"In heterogeneous catalysis, the catalytic process involves reactants and catalyst in different physical states, typically involving surface adsorption."
Syllabus Focus: Catalysis – Homogeneous and Heterogeneous
Preserved in Rationalized Curriculum Syllabus & Academic Standards ↗
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