Q.77 Chemistry · Section A ⭐ 360° Option Elimination Active

NEET 2024 Chemistry Question 77 Solution

Topic: Solutions · Official NTA Booklet Code T1

Question

The Henry's law constant (K_H) values of three gases (A, B, C) in water are 145, 2×10⁻⁵ and 35 kbar, respectively. The solubility of these gases in water follow the order:

✓

Verified Against NTA Final Answer Key

Option (4) : B > C > A

📚 Solutions Easy

📋 Given Parameters & Problem Setup

Henry’s constant for Gas A (K_H,A) 145 kbar

Henry’s constant for Gas B (K_H,B) 2 × 10^-5 kbar

Henry’s constant for Gas C (K_H,C) 35 kbar

⚡

The 30-Second Exam Hall Shortcut: ⚡ Inverse Henry Constant Rule

⏱️ Save ~30 seconds

Solubility x ∝ (1 / K_H)! Lowest K_H means HIGHEST solubility! K_H order: B (2e-5) < C (35) < A (145) -> Solubility: B > C > A!

1 Henry’s Law: p = K_H · x, where x is mole fraction solubility.

2 Rearranging gives: x = p / K_H.

3 At a constant partial pressure, gas solubility is INVERSELY proportional to Henry’s constant K_H.

4 Order of K_H: K_H(B) [2 × 10⁻⁵ kbar] < K_H(C) [35 kbar] < K_H(A) [145 kbar].

5 Therefore, solubility order is exactly inverted: B > C > A.

6 Match Option (4) in 5 seconds!

🛡️

Why You Can 100% Trust This Shortcut: NCERT Chemistry · Solutions (Henry’s law: higher the value of KH at a given pressure, the lower is the solubility of the gas in the liquid).

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Henry’s Law Mathematical Relationship

Henry’s law states that at a constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas present above the surface of the liquid or solution:

p = K_H \cdot x \implies x = \frac{p}{K_H}

Step 2

Inverse Proportionality Between Solubility and KH

From the rearranged equation, at a given constant pressure p, the mole fraction x (which measures gas solubility) is inversely proportional to the Henry’s law constant KH: Higher KH -> Lower solubility Lower KH -> Higher solubility

x \propto \frac{1}{K_H} \quad (\text{at constant } p)

Step 3

Ordering the Gases by Given KH Values

Listing the given KH values in increasing numerical order: - Gas B: KH = 2 × 10⁻⁵ kbar (exceptionally small KH -> maximum solubility) - Gas C: KH = 35 kbar (intermediate KH -> moderate solubility) - Gas A: KH = 145 kbar (largest KH -> minimum solubility)

K_H(B) \;[2\times 10^{-5}] < K_H(C) \;[35] < K_H(A) \;[145] \implies x_B > x_C > x_A

⭐

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:

Assumes direct proportionality between solubility and KH (order of KH values, not solubility).

⚠️

Student Fallacy (Why candidates pick this trap): Thinking higher KH means higher solubility.

2 (2)

✗ Incorrect

Verdict & Scientific Reason:

Completely incorrect ordering of KH values.

⚠️

Student Fallacy (Why candidates pick this trap): Misreading exponents.

3 (3)

✗ Incorrect

Verdict & Scientific Reason:

Places A above C in solubility even though KH(A) > KH(C).

⚠️

Student Fallacy (Why candidates pick this trap): Partial inversion.

4 (4)

✓ 100% Correct

Verdict & Scientific Reason:

Exact inverse ordering of Henry’s law constants: B (lowest KH) > C > A (highest KH).

💡

Why this is airtight: None.

⚠️

NTA Trap Alert: Option (1) Direct Proportionality Trap

Students frequently treat KH like an equilibrium solubility constant (Ksp) where bigger means more soluble. For Henry’s constant, BIGGER KH MEANS LESS SOLUBLE!

🛡️ How to avoid the -1 mark: Recite the verbatim NCERT phrase: "Higher the value of KH at a given pressure, lower is the solubility of the gas."

📖

Core NEET Syllabus Standard

Chemistry Core Physical Chemistry · Solutions Standard Benchmark

Core Scientific Principle Tested:

"Solubility of a gas is inversely proportional to its Henry’s law constant KH at constant pressure: x = p / KH."

Syllabus Focus: Solubility of Gases in Liquids: Henry’s Law Constant

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

High KH means gas hates the drink: Low KH lets it dissolve in a wink (B > C > A)!

Ready to attempt under real exam pressure?

Test your speed and accuracy in the authentic 200-minute timed NTA simulator.

Launch NEET 2024 CBT Test →

← Previous (Q.76) All Chemistry Questions Grid Next (Q.78) →

Spotted a mistake in this solution? Report an error (support@mycompetitiveexams.com)

⚖️ Legal & Fair Dealing Notice: Sourced from publicly released NEET 2024 question papers and NEET answer keys for private study, research, and non-commercial educational practice under Fair Dealing (Section 52(1)(a) of the Indian Copyright Act, 1957). Not affiliated with or endorsed by NTA or NMC.

NEET 2024 Chemistry Question 77 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Inverse Henry Constant Rule

Step-by-Step Rigorous Workflow & Mathematical Proof

Henry’s Law Mathematical Relationship

Inverse Proportionality Between Solubility and KH

Ordering the Gases by Given KH Values

360° Option Elimination Engine Key Feature

NTA Trap Alert: Option (1) Direct Proportionality Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Solutions

Thermodynamics & Intermolecular Forces of Ideal Solutions

Raoult's Law & Binary Liquid Mixtures Deviations

Classification of Solutions: Solute and Solvent States

Highest Boiling Point of Aqueous Solutions (Effective Molality / Osmolarity)

Solve 4 NEET Questions a Day — One per Subject