Q.86 Chemistry ⭐ 360° Option Elimination Active

NEET 2023 Chemistry Question 86 Solution

Topic: The p-Block Elements · Official NTA Booklet Code G5

Question

Match List - I (Oxoacids of Sulphur) with List - II (Bonds): List I: A. Peroxodisulphuric acid; B. Sulphuric acid; C. Pyrosulphuric acid; D. Sulphurous acid. List II: I. Two S-OH, Four S=O, One S-O-S; II. Two S-OH, One S=O; III. Two S-OH, Four S=O, One S-O-O-S; IV. Two S-OH, Two S=O. Choose the correct answer from the options given below:

✓

Verified Against NTA Final Answer Key

Option (3) : A-III, B-IV, C-I, D-II

📚 The p-Block Elements Medium

📋 Given Parameters & Problem Setup

Oxoacids (List I) A. Peroxodisulphuric acid, B. Sulphuric acid, C. Pyrosulphuric acid, D. Sulphurous acid

Bond descriptions (List II) I. Two S-OH, Four S=O, One S-O-S; II. Two S-OH, One S=O; III. Two S-OH, Four S=O, One S-O-O-S; IV. Two S-OH, Two S=O

⚡

The 30-Second Exam Hall Shortcut: ⚡ Peroxo Bridge Scan: Marshall’s Acid (H₂S₂O₈) Uniquely Contains S–O–O–S Bridge (A → III)

⏱️ Save ~35 seconds

Peroxodisulphuric acid (H₂S₂O₈) has a peroxo bridge (S–O–O–S) → A-III. This immediately eliminates Options (2) and (4). Pyrosulphuric acid (Oleum, H₂S₂O₇) has an S–O–S bridge → C-I. Matches Option (3) uniquely: A-III, B-IV, C-I, D-II in 10 seconds!

1 Match A (Peroxodisulphuric acid, H₂S₂O₈): Must contain peroxo linkage S–O–O–S → III.

2 Match B (Sulphuric acid, H₂SO₄): O=S(=O)(OH)₂ has two S=O and two S–OH → IV.

3 Match C (Pyrosulphuric acid / Oleum, H₂S₂O₇): Contains bridging S–O–S, four S=O, two S–OH → I.

4 Match D (Sulphurous acid, H₂SO₃): O=S(OH)₂ has one S=O and two S–OH → II.

5 Complete combination: A-III, B-IV, C-I, D-II (Option 3).

🛡️

Why You Can 100% Trust This Shortcut: Standard NCERT Group 16 Oxoacids of Sulphur structural diagram.

📐

Step-by-Step Rigorous Workflow & Mathematical Proof

Step 1

Structure of Peroxodisulphuric Acid (H₂S₂O₈)

Known as Marshall’s acid, each sulphur is in oxidation state +6 and is bonded to one -OH, two =O, and joined by a peroxo linkage:

\text{HO}-\text{SO}_2-\text{O}-\text{O}-\text{SO}_2-\text{OH} \implies \text{Two S-OH, Four S=O, One S-O-O-S (III)}

Step 2

Structure of Sulphuric Acid (H₂SO₄)

Sulphur is surrounded by four oxygen atoms in a tetrahedral geometry:

\text{O}=\text{S}(=\text{O})(\text{OH})_2 \implies \text{Two S-OH, Two S=O (IV)}

Step 3

Structure of Pyrosulphuric Acid (H₂S₂O₇)

Also known as oleum, formed by condensing two molecules of sulphuric acid with elimination of water:

\text{HO}-\text{SO}_2-\text{O}-\text{SO}_2-\text{OH} \implies \text{Two S-OH, Four S=O, One S-O-S (I)}

Step 4

Structure of Sulphurous Acid (H₂SO₃)

Sulphur has one lone pair, with oxidation state +4:

\text{O}=\text{S}(\text{OH})_2 \implies \text{Two S-OH, One S=O (II)}

⭐

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:

Mismatches pyrosulphuric acid with sulphurous acid.

⚠️

Student Fallacy (Why candidates pick this trap): Candidate confused the pyrosulphuric S-O-S bridge with sulphurous acid.

2 (2)

✗ Incorrect

Verdict & Scientific Reason:

Incorrect assignment of peroxo linkage to pyrosulphuric acid.

⚠️

Student Fallacy (Why candidates pick this trap): Candidate confused peroxo (-O-O-) with oxo (-O-) bridging.

3 (3)

✓ 100% Correct

Verdict & Scientific Reason:

Accurate: Fully matches structural formulas of all four oxoacids of sulphur.

💡

Why this is airtight: None. Candidate correctly identified all bridging and terminal bonds.

4 (4)

✗ Incorrect

Verdict & Scientific Reason:

Swaps Marshall’s acid and oleum bond distributions.

⚠️

Student Fallacy (Why candidates pick this trap): Candidate inverted Marshall’s acid and oleum bridges.

⚠️

NTA Trap Alert: Mixing up Peroxodisulphuric and Pyrosulphuric Acid

Both H₂S₂O₈ and H₂S₂O₇ have two S-OH and four S=O bonds. The ONLY structural difference is the central bridge: H₂S₂O₈ has a peroxo bridge (S-O-O-S), while H₂S₂O₇ has an ether-like oxygen bridge (S-O-S).

🛡️ How to avoid the -1 mark: Mnemonic: "Peroxo has Pair of oxygens (O-O)".

📖

Core NEET Syllabus Standard

National Eligibility cum Entrance Test (NEET UG) · The p-Block Elements Standard Benchmark

Core Scientific Principle Tested:

"Oxoacids of sulphur display varied coordination with characteristic S=O, S-OH, S-O-S, and peroxo S-O-O-S linkages."

Syllabus Focus: Group 16 Elements – Oxoacids of Sulphur

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.85) All Chemistry Questions Grid Next (Q.87) →

Spotted a mistake in this solution? Report an error ([email protected])

⚖️ 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 86 Solution

Question

The 30-Second Exam Hall Shortcut: ⚡ Peroxo Bridge Scan: Marshall’s Acid (H₂S₂O₈) Uniquely Contains S–O–O–S Bridge (A → III)

Step-by-Step Rigorous Workflow & Mathematical Proof

Structure of Peroxodisulphuric Acid (H₂S₂O₈)

Structure of Sulphuric Acid (H₂SO₄)

Structure of Pyrosulphuric Acid (H₂S₂O₇)

Structure of Sulphurous Acid (H₂SO₃)

360° Option Elimination Engine Key Feature

NTA Trap Alert: Mixing up Peroxodisulphuric and Pyrosulphuric Acid

Core NEET Syllabus Standard

Ready to attempt under real exam pressure?

🔗 Related Questions — The p-Block Elements

Hydrides and Oxides of Group 15 Elements (Arsine and Antimony Pentoxide)

Hybridization and Molecular Geometries of Xenon Fluorides and Oxides

Boiling Points of Group 16 Hydrides and Anomalous Properties of Water

Oxidation States of Group 16 Chalcogens and Anomalous Behavior of Polonium

Solve 4 NEET Questions a Day — One per Subject