Q.69 Chemistry ⭐ 360° Option Elimination Active

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NEET 2021 Chemistry Question 69 Solution

Topic: General Principles and Processes of Isolation of Elements · Official NTA Booklet Code M1

Question

The maximum temperature that can be achieved in blast furnace is:

(1)upto 1200 K
(2)upto 2200 K
(3)upto 1900 K
(4)upto 5000 K

✓

Verified Against NTA Final Answer Key

Option (2) : upto 2200 K

📚 General Principles and Processes of Isolation of Elements Easy

📋 Given Parameters & Problem Setup

Industrial Apparatus Blast furnace for iron extraction

Target Maximum temperature achieved in the furnace

⚡

The 30-Second Exam Hall Shortcut: ⚡ Combustion Zone Tuyeres: ~2200 K

⏱️ Save ~15 seconds

Near the base of the blast furnace where preheated air blasts through tuyeres, exothermic combustion of coke ( $C + O_2 \to CO_2$ ) elevates temperature to its maximum of $\approx 2200\text{ K}$ . As hot gases ascend, temperature cools from $2200\text{ K}$ at the bottom to $\approx 500-800\text{ K}$ at the top! Match Option (2)!

1 Blast furnace temperature profile ranges from

\approx 500\text{ K}

at the top to

\approx 2200\text{ K}

at the bottom.

2 At the combustion zone near tuyeres:

C + O_2 \to CO_2

(strongly exothermic,

\Delta H = -393.5\text{ kJ/mol}

3 Maximum temperature reached in this lower combustion zone is upto

2200\text{ K}

4 Match Option (2).

🛡️

Why You Can 100% Trust This Shortcut: Canonical NCERT Metallurgy section and blast furnace diagram schematic.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Thermal Zonation in a Blast Furnace

In the industrial metallurgy of iron (extraction from haematite $Fe_2O_3$ ), the blast furnace exhibits a continuous vertical temperature gradient: - Top Zone (Reduction Zone): $500\text{ K} - 800\text{ K}$ - Middle Zone (Slag Formation & Reduction of FeO): $900\text{ K} - 1500\text{ K}$ - Lower Zone (Combustion & Fusion Zone): $1500\text{ K} - 2200\text{ K}$

Step 2

Combustion Zone Chemical Reactions

At the bottom of the blast furnace, oxygen in the blast of hot air burns descending coke to generate carbon dioxide and immense thermal energy:

C(s) + O_2(g) \longrightarrow CO_2(g), \quad \Delta H^circ = -393.5\text{ kJ/mol}

Step 3

Maximum Attainable Temperature

According to NCERT Metallurgy, the intense heat released in this localized exothermic reaction drives the temperature up to about 2200 K in the combustion zone.

T_{\text{max}} \approx 2200\text{ K}

⭐

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:

This is the intermediate temperature in the middle zone (reduction of FeO and limestone decomposition), not the maximum.

⚠️

Student Fallacy (Why candidates pick this trap): Confusing middle reduction zone temperature with combustion zone.

2 2

✓ 100% Correct

Verdict & Scientific Reason:

Verbatim NCERT specification for the maximum temperature attained in the blast furnace combustion zone.

💡

Why this is airtight: None; precise textbook recall.

3 3

✗ Incorrect

Verdict & Scientific Reason:

Close but below the peak combustion temperature of 2200 K.

⚠️

Student Fallacy (Why candidates pick this trap): Underestimating peak combustion temperature.

4 4

✗ Incorrect

Verdict & Scientific Reason:

Unrealistically high; such extreme temperatures would melt the refractory brick lining.

⚠️

Student Fallacy (Why candidates pick this trap): Overestimating furnace operational limits.

⚠️

NTA Trap Alert: Reduction Temperature vs. Maximum Combustion Temperature Trap

Students frequently remember temperatures like $1073\text{ K}$ (where the Ellingham curves intersect) or $1200\text{ K}$ (reduction of FeO by C), and confuse them with the MAXIMUM temperature in the furnace, which reaches $2200\text{ K}$ at the tuyere level.

🛡️ How to avoid the -1 mark: Max temperature in blast furnace =

2200\text{ K}

(bottom combustion zone).

📖

Core NEET Syllabus Standard

NCERT Chemistry · General Principles and Processes of Isolation of Elements Standard Benchmark

Core Scientific Principle Tested:

"In the lower combustion zone of the blast furnace, burning of coke produces temperatures up to about 2200 K."

Syllabus Focus: Extraction of Iron from its Oxides (Blast Furnace)

✓ Core NEET UG Syllabus Anchor Syllabus & Academic Standards ↗

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NEET 2021 Chemistry Question 69 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Combustion Zone Tuyeres: ~2200 K

Step-by-Step Rigorous Workflow & Mathematical Proof

Thermal Zonation in a Blast Furnace

Combustion Zone Chemical Reactions

Maximum Attainable Temperature

360° Option Elimination Engine Key Feature

NTA Trap Alert: Reduction Temperature vs. Maximum Combustion Temperature Trap

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — General Principles and Processes of Isolation of Elements

Temperature Zones and Reactions in the Blast Furnace

Metallurgy Statements: Pig Iron, Cast Iron, Blister Copper & Vapour Phase Refining

Refining of Metals: Distillation for Low-Boiling and Liquid Metals

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