Q.97 Chemistry ⭐ 360° Option Elimination Active

NEET 2023 Chemistry Question 97 Solution

Topic: General Principles and Processes of Isolation of Elements · Official NTA Booklet Code G5

Question

The reaction that does NOT take place in a blast furnace between 900K to 1500K temperature range during extraction of iron is:

✓

Verified Against NTA Final Answer Key

Option (2) : Fe₂O₃ + CO → 2FeO + CO₂

📚 General Principles and Processes of Isolation of Elements Medium

📋 Given Parameters & Problem Setup

Process Extraction of iron in blast furnace

Specified temperature range 900 K to 1500 K (higher temperature zone)

Question requirement Reaction that does NOT take place in this range

⚡

The 30-Second Exam Hall Shortcut: ⚡ Blast Furnace Thermal Zone Division: Reduction of Fe₂O₃ Occurs at Top (500–800 K)!

⏱️ Save ~30 seconds

In a blast furnace, reduction of haematite (Fe₂O₃) by CO occurs at the TOP in the LOWER temperature zone (500 K – 800 K): Fe₂O₃ + CO ⟶ 2 FeO + CO₂. The higher temperature zone (900 K – 1500 K) in the middle/lower part features C + CO₂ ⟶ 2 CO, FeO + CO ⟶ Fe + CO₂, and slag formation CaO + SiO₂ ⟶ CaSiO₃! Therefore, reaction (2) does NOT occur in 900–1500 K! Lock Option (2) in 10 seconds!

1 Check Lower Temperature Range (500 K – 800 K, top of furnace):

2 - 3 Fe₂O₃ + CO ⟶ 2 Fe₃O₄ + CO₂

3 - Fe₃O₄ + 4 CO ⟶ 3 Fe + 4 CO₂

4 - Fe₂O₃ + CO ⟶ 2 FeO + CO₂

5 Check Higher Temperature Range (900 K – 1500 K, middle/lower furnace):

6 - C + CO₂ ⟶ 2 CO

7 - FeO + CO ⟶ Fe + CO₂

8 - CaCO₃ ⟶ CaO + CO₂

9 - CaO + SiO₂ ⟶ CaSiO₃ (slag formation)

10 Reaction (2) belongs exclusively to 500–800 K, so it does NOT take place in 900–1500 K.

11 Match Option (2) directly.

🛡️

Why You Can 100% Trust This Shortcut: Verbatim NCERT Metallurgy Figure 6.6 & Blast Furnace thermal zone descriptions.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Thermal Profile of the Blast Furnace

The blast furnace is divided into thermal zones based on height: (a) Upper lower-temperature zone (500 K to 800 K), and (b) Middle-to-lower higher-temperature zone (900 K to 1500 K):

\text{Zones: } \underbrace{500\text{ K} - 800\text{ K}}_{\text{Upper (Reduction of } \text{Fe}_2\text{O}_3)} \quad \longleftrightarrow \quad \underbrace{900\text{ K} - 1500\text{ K}}_{\text{Middle/Lower (Reduction of FeO, Slag, CO gen)}}

Step 2

Reactions in the Lower Temperature Range (500 K – 800 K)

At the top of the furnace, haematite (Fe₂O₃) is reduced in stages by carbon monoxide at 500 K – 800 K:

\begin{aligned} 3\text{Fe}_2\text{O}_3 + \text{CO} &\longrightarrow 2\text{Fe}_3\text{O}_4 + \text{CO}_2 \\ \text{Fe}_3\text{O}_4 + 4\text{CO} &\longrightarrow 3\text{Fe} + 4\text{CO}_2 \\ \text{Fe}_2\text{O}_3 + \text{CO} &\longrightarrow 2\text{FeO} + \text{CO}_2 \quad (\text{Occurs at } 500\text{ K} - 800\text{ K}) \end{aligned}

Step 3

Reactions in the Higher Temperature Range (900 K – 1500 K)

In the 900 K to 1500 K zone, carbon dioxide is reduced by coke, FeO is reduced to iron, and limestone forms slag:

\begin{aligned} \text{C} + \text{CO}_2 &\longrightarrow 2\text{CO} \\ \text{FeO} + \text{CO} &\longrightarrow \text{Fe} + \text{CO}_2 \\ \text{CaCO}_3 &\longrightarrow \text{CaO} + \text{CO}_2 \\ \text{CaO} + \text{SiO}_2 &\longrightarrow \text{CaSiO}_3 \quad (\text{Slag formation}) \end{aligned}

Step 4

Identify the Reaction that Does NOT Take Place in 900–1500 K

Reaction (2), Fe₂O₃ + CO ⟶ 2 FeO + CO₂, takes place strictly at the lower temperatures (500 K – 800 K). Therefore, it does NOT occur in the 900 K to 1500 K range:

\text{Fe}_2\text{O}_3 + \text{CO} \longrightarrow 2\text{FeO} + \text{CO}_2 \quad (\text{Does NOT occur at } 900\text{ K} - 1500\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:

Slag formation occurs actively between 1070 K and 1270 K (inside 900 K – 1500 K).

⚠️

Student Fallacy (Why candidates pick this trap): Candidate forgot the temperature of slag formation in the middle zone.

2 (2)

✓ 100% Correct

Verdict & Scientific Reason:

Accurate: This reduction step occurs at the cooler top of the blast furnace (500 K – 800 K), not between 900 K and 1500 K.

💡

Why this is airtight: None. Candidate correctly correlated reaction thermodynamics with furnace temperature zones.

3 (3)

✗ Incorrect

Verdict & Scientific Reason:

Reduction of FeO to Fe takes place directly within the 900 K – 1500 K range.

⚠️

Student Fallacy (Why candidates pick this trap): Candidate confused the reduction of FeO with the reduction of Fe₂O₃.

4 (4)

✗ Incorrect

Verdict & Scientific Reason:

The endothermic Boudouard reaction occurs at high temperatures (around 1000 K – 1200 K).

⚠️

Student Fallacy (Why candidates pick this trap): Candidate did not recognize that coke reduction of CO₂ requires high temperature.

⚠️

NTA Trap Alert: Confusing Low and High Temperature Reduction Steps

Students remember that CO reduces iron oxides throughout the furnace, but forget that Fe₂O₃ is reduced to FeO at the top (cooler zone, 500–800 K), and FeO is reduced to molten Fe in the hotter zone (900–1500 K).

🛡️ How to avoid the -1 mark: Remember: Fe₂O₃ reduction = Top (cooler, 500–800 K); FeO reduction + Slag formation = Middle/Bottom (hotter, 900–1500 K).

📖

Core NEET Syllabus Standard

National Eligibility cum Entrance Test (NEET UG) · General Principles and Processes of Isolation of Elements Standard Benchmark

Core Scientific Principle Tested:

"Reduction of Fe₂O₃ by CO proceeds in the upper low-temperature zone (500–800 K); reduction of FeO and slag formation occur at 900–1500 K."

Syllabus Focus: Extraction of Iron from its Oxides – Blast Furnace

Preserved in Rationalized Curriculum Syllabus & Academic Standards ↗

Ready to attempt under real exam pressure?

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

Launch NEET 2023 CBT Test →

← Previous (Q.96) All Chemistry Questions Grid Next (Q.98) →

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

View Solution →

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

⚖️ Legal & Fair Dealing Notice: Sourced from publicly released NEET 2023 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 2023 Chemistry Question 97 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Blast Furnace Thermal Zone Division: Reduction of Fe₂O₃ Occurs at Top (500–800 K)!

Step-by-Step Rigorous Workflow & Mathematical Proof

Thermal Profile of the Blast Furnace

Reactions in the Lower Temperature Range (500 K – 800 K)

Reactions in the Higher Temperature Range (900 K – 1500 K)

Identify the Reaction that Does NOT Take Place in 900–1500 K

360° Option Elimination Engine Key Feature

NTA Trap Alert: Confusing Low and High Temperature Reduction Steps

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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

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

Metallurgy of Iron: Maximum Temperature Achieved in Blast Furnace

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

Solve 4 NEET Questions a Day — One per Subject