Q.63 Chemistry ⭐ 360° Option Elimination Active

NEET 2026 Chemistry Question 63 Solution

Topic: Some Basic Concepts of Chemistry · Official NTA Booklet Code 50

Question

The amount of carbon dioxide evolved upon complete combustion of 116 g of n-butane is (Given: atomic mass in amu H = 1, C = 12 and O = 16)

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Verified Against NTA Final Answer Key

Option (1) : 352 g

📚 Some Basic Concepts of Chemistry Easy

📋 Given Parameters & Problem Setup

Reactant n-butane (C₄H₁₀)

Mass of n-butane 116 g

Atomic Masses H = 1, C = 12, O = 16 amu

Target Mass of CO₂ evolved upon complete combustion

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The 30-Second Exam Hall Shortcut: ⚡ Mole-Ratio Direct Multiplier

⏱️ Save ~50 seconds

Molar mass of butane is 58 g/mol -> 116 g is exactly 2 moles of butane!

1 Molar mass of C₄H₁₀ = (4 × 12) + (10 × 1) = 58 g/mol.

2 Moles of butane = 116 g / 58 g/mol = 2.0 moles.

3 Each butane molecule has 4 carbon atoms, producing 4 CO₂ molecules: Moles of CO₂ = 2 × 4 = 8 moles.

4 Molar mass of CO₂ = 12 + (2 × 16) = 44 g/mol.

5 Mass of CO₂ = 8 moles × 44 g/mol = 352 g!

6 Option (1) selected in 15 seconds!

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Why You Can 100% Trust This Shortcut: Law of conservation of mass: All carbon in the hydrocarbon quantitatively converts to CO₂ upon complete combustion.

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Write the Balanced Chemical Equation for Combustion

Complete combustion of an alkane (C_n H_{2n+2}) with excess oxygen yields carbon dioxide and water vapor.

\text{C}_4\text{H}_{10} + \frac{13}{2}\text{O}_2 \longrightarrow 4\text{CO}_2 + 5\text{H}_2\text{O}

• 1 mole of n-butane produces 4 moles of CO₂.

Step 2

Calculate Moles of n-butane Burned

Determine the molecular mass of n-butane and calculate the number of moles in 116 g.

M(\text{C}_4\text{H}_{10}) = 4(12) + 10(1) = 58\text{ g mol}^{-1}

• n(butane) = 116 g / 58 g mol⁻¹ = 2.0 mol.

Step 3

Calculate Mass of CO₂ Formed

Using stoichiometry, 2.0 moles of butane produce 8.0 moles of CO₂.

n(\text{CO}_2) = 2.0 \times 4 = 8.0\text{ mol}

• M(CO₂) = 12 + 2(16) = 44 g mol⁻¹.
• Mass of CO₂ = 8.0 mol × 44 g mol⁻¹ = 352 g.
• Matches Option (1).

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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:

Stoichiometrically exact: 2 moles of butane yield 8 moles of CO₂ = 352 g.

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Why this is airtight: None; standard stoichiometric execution.

2 B

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Arithmetic miscalculation.

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Student Fallacy (Why candidates pick this trap): Multiplication error when computing 8 × 44.

3 C

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Corresponds to 1 mole of butane instead of 2 moles: 4 × 44 = 176 g.

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Student Fallacy (Why candidates pick this trap): Forgetting to multiply by 2 moles of butane.

4 D

✗ Incorrect

Verdict & Scientific Reason:

Incorrect. Distractor value.

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Student Fallacy (Why candidates pick this trap): Using incorrect atomic weight for carbon or hydrogen.

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NTA Trap Alert: Calculating for 1 Mole Instead of the Given 116 g

Students frequently compute 4 × 44 = 176 g (Option 3) for 1 mole of butane and forget that 116 g contains TWO moles of butane.

🛡️ How to avoid the -1 mark: Always convert given mass to moles FIRST before applying mole ratios.

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Core NEET Syllabus Standard

NEET Chemistry Core Syllabus · Some Basic Concepts of Chemistry Standard Benchmark

Core Scientific Principle Tested:

"Each mole of C_n H_{2n+2} produces n moles of CO₂ upon complete combustion."

Syllabus Focus: Stoichiometric calculations and combustion reactions

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

116 g is 2 moles of butane; 2 × 4 = 8 moles of CO₂; 8 × 44 = 352 g!

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NEET 2026 Chemistry Question 63 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Mole-Ratio Direct Multiplier

Step-by-Step Rigorous Workflow & Mathematical Proof

Write the Balanced Chemical Equation for Combustion

Calculate Moles of n-butane Burned

Calculate Mass of CO₂ Formed

360° Option Elimination Engine Key Feature

NTA Trap Alert: Calculating for 1 Mole Instead of the Given 116 g

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — Some Basic Concepts of Chemistry

Limitations of Dalton’s Atomic Theory: Inability to Explain Gay-Lussac’s Law of Gaseous Volumes

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