Q.88 Chemistry ⭐ 360° Option Elimination Active

NEET 2025 Chemistry Question 88 Solution

Topic: Equilibrium · Official NTA Booklet Code 45

Question

Higher yield of NO in N₂(g) + O₂(g) ⇌ 2NO(g) can be obtained at [ΔH of the reaction = +180.7 kJ mol⁻¹] A. higher temperature B. lower temperature C. higher concentration of N₂ D. higher concentration of O₂ Choose the correct answer from the options given below:

✓

Verified Against NTA Final Answer Key

Option (4) : A, C, D only

📚 Equilibrium Easy

📋 Given Parameters & Problem Setup

Reversible Reaction N₂(g) + O₂(g) ⇌ 2NO(g)

Reaction Enthalpy (ΔH) +180.7 kJ mol⁻¹ (Endothermic)

Conditions Evaluated A: Higher temperature, B: Lower temperature, C: Higher [N₂], D: Higher [O₂]

⚡

The 30-Second Exam Hall Shortcut: ⚡ Le Chatelier Forward Shift Rule

⏱️ Save ~25 seconds

ΔH is POSITIVE (+180.7 kJ/mol) ⟹ Forward reaction ABSORBS heat! Higher temperature shifts equilibrium FORWARD to higher yield (A is correct)! Adding reactants (higher [N₂] or [O₂]) shifts equilibrium FORWARD to consume them (C and D are correct)! ⟹ A, C, D only!

1 Examine reaction: N₂(g) + O₂(g) ⇌ 2NO(g) with ΔH = +180.7 kJ/mol (endothermic forward reaction).

2 Temperature effect: According to Le Chatelier’s principle, increasing temperature shifts equilibrium in the direction of the endothermic reaction (forward direction) ⟹ Higher yield of NO! Condition A is TRUE; B is FALSE.

3 Concentration effect: Increasing the concentration of reactants ([N₂] or [O₂]) disturbs equilibrium, causing the forward reaction to proceed to consume added reactants ⟹ Higher yield of NO! Conditions C and D are TRUE.

4 Conclusion: Higher yield of NO is obtained at A, C, and D only.

5 Select Option (4) in under 10 seconds!

🛡️

Why You Can 100% Trust This Shortcut: Le Chatelier’s Principle on Chemical Equilibria (NCERT Chemistry · Equilibrium).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Apply Le Chatelier’s Principle for Temperature Change

For an endothermic reversible reaction (ΔH > 0), absorption of heat accompanies the forward reaction:

\text{N}_2(g) + \text{O}_2(g) + \text{Heat} \rightleftharpoons 2\text{NO}(g), \quad \Delta H = +180.7\text{ kJ}\cdot\text{mol}^{-1}

• An increase in temperature supplies thermal energy, driving the system to absorb heat by shifting to the right (forward).
• Consequently, higher temperature (A) increases the equilibrium constant K_p and enhances the yield of NO.
• Condition A is correct; condition B is incorrect.

Step 2

Apply Le Chatelier’s Principle for Reactant Concentrations

Examine the reaction quotient Q_c when reactant concentrations are increased:

Q_c = \frac{[\text{NO}]^2}{[\text{N}_2][\text{O}_2]}

• Increasing [N₂] or [O₂] makes Q_c < K_c, driving the reaction in the forward direction until Q_c = K_c again.
• Therefore, higher concentration of N₂ (C) and higher concentration of O₂ (D) both increase the yield of NO.

Step 3

Synthesize the Resulting Favorable Conditions

Combine all favorable operational parameters:

\text{Favorable conditions: } \text{Higher Temperature (A)} \cup \text{Higher [N}_2\text{] (C)} \cup \text{Higher [O}_2\text{] (D)}

• Matches Option (4) A, C, D only.

⭐

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

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Omits higher concentration of N₂ (C).

⚠️

Student Fallacy (Why candidates pick this trap): Leaving out condition C.

2 B

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Lower temperature (B) favors the backward exothermic reaction, reducing NO yield.

⚠️

Student Fallacy (Why candidates pick this trap): Thinking lower temperature favors endothermic reactions.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Includes lower temperature (B).

⚠️

Student Fallacy (Why candidates pick this trap): Confusing endothermic with exothermic temperature response.

4 D

✓ 100% Correct

Verdict & Scientific Reason:

100% correct. Higher temperature (endothermic shift) and higher reactant concentrations shift equilibrium to NO.

💡

Why this is airtight: None; flawless application of Le Chatelier’s principle.

⚠️

NTA Trap Alert: Confusing Endothermic with Haber Process (Exothermic)

In the Haber synthesis of NH₃, the reaction is EXOTHERMIC, so lower temperature gives higher yield. But NO formation is ENDOTHERMIC (+180.7 kJ/mol), so HIGHER temperature is required for high yield!

🛡️ How to avoid the -1 mark: Check the sign of ΔH: +ΔH means Heat is a reactant ⟹ Higher T shifts forward!

📖

Core NEET Syllabus Standard

NEET Chemistry Core Syllabus · Equilibrium Standard Benchmark

Core Scientific Principle Tested:

"For endothermic reactions (ΔH > 0), higher temperature and higher reactant concentrations increase product yield."

Syllabus Focus: Factors Affecting Equilibria: Le Chatelier’s Principle

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

Heat is a reactant (+ΔH) ⟹ More Heat (A) + More Reactants (C, D) = More NO (Option 4)!

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NEET 2025 Chemistry Question 88 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Le Chatelier Forward Shift Rule

Step-by-Step Rigorous Workflow & Mathematical Proof

Apply Le Chatelier’s Principle for Temperature Change

Apply Le Chatelier’s Principle for Reactant Concentrations

Synthesize the Resulting Favorable Conditions

360° Option Elimination Engine Key Feature

NTA Trap Alert: Confusing Endothermic with Haber Process (Exothermic)

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Equilibrium

Comparison of Molar Solubility from Solubility Product Constants (Ksp)

Direction of Reaction by Comparing Reaction Quotient (Qc) with Equilibrium Constant (Kc)

Relationship Between Kp and Kc (Δng Condition)

Equilibrium Constant and Degree of Dissociation (α) of NO(g)

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