Q.60 Chemistry ⭐ 360° Option Elimination Active

NEET 2023 Chemistry Question 60 Solution

Topic: Hydrogen · Official NTA Booklet Code G5

Question

Which of the following statements are NOT correct? A. Hydrogen is used to reduce heavy metal oxides to metals. B. Heavy water is used to study reaction mechanism. C. Hydrogen is used to make saturated fats from oils. D. The H-H bond dissociation enthalpy is lowest as compared to a single bond between two atoms of any element. E. Hydrogen reduces oxides of metals that are more active than iron. Choose the most appropriate answer from the options given below:

✓

Verified Against NTA Final Answer Key

Option (4) : D, E only

📚 Hydrogen Easy

📋 Given Parameters & Problem Setup

Statement A Used to reduce heavy metal oxides to metals

Statement B Heavy water is used to study reaction mechanisms

Statement C Used to make saturated fats from oils

Statement D H-H bond dissociation enthalpy is lowest for any single bond

Statement E Reduces oxides of metals more active than iron

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The 30-Second Exam Hall Shortcut: ⚡ Fact Elimination Hack: H-H Has HIGHEST Single Bond Energy!

⏱️ Save ~40 seconds

H-H bond enthalpy (435.9 kJ/mol) is the HIGHEST single bond enthalpy of any element, not lowest ⟹ D is FALSE! H₂ CANNOT reduce oxides of metals more active than Fe (Na, Mg, Al) ⟹ E is FALSE! Option (4) in 15 seconds!

1 Check Statement D: The H–H bond dissociation enthalpy is 435.88 kJ mol⁻¹, which is the HIGHEST (not lowest) for a single bond between two atoms of any element. Thus D is INCORRECT.

2 Check Statement E: Highly electropositive metals (more active than iron, like Na, Mg, Al, Zn) have higher oxygen affinity than hydrogen; their oxides cannot be reduced by H₂. Thus E is INCORRECT.

3 Check Statements A, B, C: All are standard, correct NCERT statements (A: metallurgy of W, Mo, Cu; B: D₂O isotopic tracer; C: hydrogenation of vegetable oils).

4 The question asks for statements that are NOT correct ⟶ D and E only.

5 Lock Option (4) D, E only immediately!

🛡️

Why You Can 100% Trust This Shortcut: Inorganic Chemistry · Dihydrogen Properties (The H-H single bond enthalpy is the highest known for any single homonuclear bond, and dihydrogen reduces only oxides of metals less active than iron).

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Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Analysis of Statement A (Metallurgical Reduction)

Dihydrogen is used in metallurgy to reduce oxides of metals less active than iron (such as tungsten, molybdenum, copper) to their respective elemental metals at elevated temperatures. Therefore, Statement A is correct.

\text{WO}_3 + 3\text{H}_2 \xrightarrow{\Delta} \text{W} + 3\text{H}_2\text{O} \quad (\text{Correct})

Step 2

Analysis of Statement B (Heavy Water as Tracer)

Heavy water (D₂O) is extensively employed as an isotopic tracer to elucidate organic and biochemical reaction mechanisms by tracking deuterium exchange. Therefore, Statement B is correct.

\text{D}_2\text{O} \text{ serves as an isotopic tracer in mechanism studies } (\text{Correct})

Step 3

Analysis of Statement C (Industrial Hydrogenation)

Hydrogenation of polyunsaturated vegetable oils using finely divided nickel catalyst at ~473 K yields saturated edible fats (vanaspati ghee). Therefore, Statement C is correct.

\text{Vegetable oil (liquid)} + \text{H}_2 \xrightarrow{\text{Ni, } \Delta} \text{Vanaspati fat (solid)} \quad (\text{Correct})

Step 4

Analysis of Statement D (H–H Bond Dissociation Enthalpy)

Owing to the small size of hydrogen atoms and the effective overlap of 1s orbitals, the H–H bond dissociation enthalpy is 435.88 kJ mol⁻¹, which is the HIGHEST for a single bond between two atoms of any element. Statement D falsely claims it is the lowest, making Statement D INCORRECT.

\Delta_{\text{bond}}H(\text{H}-\text{H}) = 435.88\text{ kJ mol}^{-1} \quad (\text{Highest, not lowest } \implies \text{INCORRECT})

Step 5

Analysis of Statement E (Activity Series and Oxide Reduction)

Hydrogen can reduce only the oxides of metals that are less electropositive than iron in the activity series (e.g., CuO, PbO, Fe₂O₃ under vigorous conditions). It CANNOT reduce oxides of metals more active than iron (such as Na, K, Ca, Mg, Al). Therefore, Statement E is INCORRECT.

\text{H}_2 + \text{MgO} \centernot\longrightarrow \text{Mg} + \text{H}_2\text{O} \quad (\text{INCORRECT})

⭐

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:

These are the correct statements, but the question asks for NOT correct statements.

⚠️

Student Fallacy (Why candidates pick this trap): Candidate misread "NOT correct" and selected the true statements.

2 (2)

✗ Incorrect

Verdict & Scientific Reason:

Incorrectly includes true statements B and C.

⚠️

Student Fallacy (Why candidates pick this trap): Candidate doubted the uses of heavy water and hydrogenation.

3 (3)

✗ Incorrect

Verdict & Scientific Reason:

B is true; omits false statement E.

⚠️

Student Fallacy (Why candidates pick this trap): Candidate did not evaluate metal activity series.

4 (4)

✓ 100% Correct

Verdict & Scientific Reason:

Accurate: Both D (claims lowest bond enthalpy) and E (claims reduction of metals more active than Fe) are false.

💡

Why this is airtight: None. Candidate carefully isolated the two incorrect claims.

⚠️

NTA Trap Alert: Misreading "NOT correct" and Picking the Correct Statements (A, B, C)

Under examination stress, candidates frequently ignore the bold word "NOT" and hurriedly choose Option (1) "A, B, C only" because they recognize them as familiar facts from the textbook.

🛡️ How to avoid the -1 mark: Circle the negative word: "NOT correct" means find the FALSE statements (D and E).

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Core NEET Syllabus Standard

National Eligibility cum Entrance Test (NEET UG) · Hydrogen Standard Benchmark

Core Scientific Principle Tested:

"The H-H bond enthalpy is the highest for a single bond of any element, and dihydrogen reduces only oxides of metals less active than iron."

Syllabus Focus: Chemical Properties and Uses of Dihydrogen

Preserved in Rationalized Curriculum Syllabus & Academic Standards ↗

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NEET 2023 Chemistry Question 60 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Fact Elimination Hack: H-H Has HIGHEST Single Bond Energy!

Step-by-Step Rigorous Workflow & Mathematical Proof

Analysis of Statement A (Metallurgical Reduction)

Analysis of Statement B (Heavy Water as Tracer)

Analysis of Statement C (Industrial Hydrogenation)

Analysis of Statement D (H–H Bond Dissociation Enthalpy)

Analysis of Statement E (Activity Series and Oxide Reduction)

360° Option Elimination Engine Key Feature

NTA Trap Alert: Misreading "NOT correct" and Picking the Correct Statements (A, B, C)

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

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