This summary lists the most commonly made errors in INC-03 that cost marks in NEET.

Geometry Errors:

• WRONG: XeF2 is angular/bent. CORRECT: XeF2 is LINEAR (3 equatorial lone pairs push F to axial positions)
• WRONG: XeF4 is tetrahedral. CORRECT: XeF4 is SQUARE PLANAR (2 trans lone pairs in octahedral)
• WRONG: SO3 is angular like SO2. CORRECT: SO3 is TRIGONAL PLANAR (no lone pair on central S)
• WRONG: ClF3 is trigonal planar. CORRECT: ClF3 is T-SHAPED (2 equatorial lone pairs)

Contact Process Errors:

• WRONG: SO3 is dissolved directly in water → H2SO4. CORRECT: SO3 is absorbed in conc. H2SO4 → oleum first
• WRONG: Catalyst in Step 2 is Pt. CORRECT: Catalyst is V2O5 (Pt is too expensive and easily poisoned)
• WRONG: Step 2 reaction is irreversible. CORRECT: It is a REVERSIBLE equilibrium (⇌)
• WRONG: Contact process temperature is 800°C. CORRECT: ~450°C (compromise temperature)

Acid Strength Errors:

• WRONG: HF is the strongest hydrogen halide acid (most electronegative F). CORRECT: HF is the WEAKEST
• WRONG: HOCl is stronger than HClO4. CORRECT: HClO4 is the STRONGEST chlorine oxoacid

Noble Gas/Halogen Errors:

• WRONG: Fluorine forms HOF as an oxoacid. CORRECT: Fluorine forms NO oxoacids (lacks d-orbitals)
• WRONG: Cl2 can displace F2 from a fluoride salt. CORRECT: Cl2 is a weaker oxidizer — cannot displace F2