CBSE Class 12 Chemistry: Updated Inorganic Chemistry Guide (2025-26 Syllabus)

📚 STUDY
⚠️ Important Update: This guide is specifically for the CBSE Class 12 Chemistry syllabus (2025-26 session), applicable for Board exams in 2026. Several chapters have been permanently deleted as part of the rationalized/reduced syllabus.

🗑️ Deleted Chapters (Full Removal) in Class 12 Chemistry 2025-26

The following entire units have been completely removed from the syllabus:

  • Unit 1: The Solid State (Physical Chemistry)
  • Unit 5: Surface Chemistry (Physical Chemistry)
  • Unit 6: General Principles and Processes of Isolation of Elements (Inorganic - Metallurgy)
  • Unit 7: The p-Block Elements (Inorganic - Groups 15-18)

Additional deletions: Polymers, Chemistry in Everyday Life, and Biomolecules (full chapters), plus parts of some organic chapters (e.g., cyanides/isocyanides removed, now only Amines remain).

📌 Note: Questions from older PYQs (2020-2024) on p-block and metallurgy are no longer relevant—skip them completely.

📚 Updated Focus for Inorganic Chemistry (Remaining Portions)

With General Principles and Processes of Isolation of Elements and The p-Block Elements completely removed, inorganic chemistry now primarily consists of only two high-weightage chapters:

1. The d- and f-Block Elements Unit 8

  • Weightage: Usually 5-7 marks (sometimes up to 8 marks)
  • This remains one of the most important inorganic sections.

2. Coordination Compounds Unit 9

  • Weightage: Usually 6-8 marks
  • This is still the highest-weightage inorganic chapter and very consistent in exams.

Total inorganic weightage: Now ~12-15 marks instead of 18-20, but these two chapters are heavily tested every year.

🎯 Most Important & Most Repeated Questions (Based on Last 5 Years Trends)

These repetitions are based on 2021-2025 papers (even post-rationalization, patterns in d/f-block and coordination are very stable).

1. The d- and f-Block Elements

Key Repeated Topics: Variable oxidation states, magnetic properties & spin-only formula, lanthanoid contraction & consequences, catalytic properties, comparison of 3d series elements, ionization enthalpy trends, KMnO₄ and K₂Cr₂O₇ reactions/behaviour.

Question Example Type/Marks Years Repeated Notes
Why do transition elements exhibit variable oxidation states? Which element shows the maximum number of oxidation states in 3d series? Short Answer 2 marks 4-5 times (2020-2025) Mn (+2 to +7) is frequently asked.
Calculate the spin-only magnetic moment for Fe²⁺ / Cr³⁺ / Cu²⁺. Is the ion paramagnetic? Numerical 2 marks 4+ times Formula: μ = √[n(n+2)] BM; unpaired e⁻ count is key.
Explain lanthanoid contraction. Mention two consequences (e.g., similar properties of Zr & Hf). Reasoning 3 marks 3-4 times Often in assertion-reason or case-based.
Why is KMnO₄ a stronger oxidizing agent in acidic medium? Give a balanced equation with oxalic acid / Fe²⁺. Case-based or Short 3-4 marks 3+ times Color change, titration-related repeated.
Compare the properties of lanthanoids and actinoids (oxidation states, radioactivity, etc.). Short Answer 2-3 marks 2-3 times Actinoids more reactive, variable states.

2. Coordination Compounds

Key Repeated Topics: IUPAC nomenclature, isomerism (geometrical, linkage, ionization), VBT (hybridization & geometry), CFT (crystal field splitting, ∆o > ∆t, spectrochemical series, color, magnetic nature), applications (haemoglobin, vitamin B12).

Question Example Type/Marks Years Repeated Notes
For [Co(NH₃)₆]³⁺ and [CoF₆]³⁻: Determine hybridization, geometry, magnetic nature (low spin vs high spin), and number of unpaired electrons. Short Answer 2-3 marks 5+ times NH₃ = strong field (diamagnetic), F⁻ = weak field (paramagnetic).
Explain why octahedral splitting energy (∆o) is greater than tetrahedral (∆t). Draw d-orbital splitting diagrams. Reasoning 3 marks 3-4 times 9:4 ratio, spectrochemical series (I⁻ < Br⁻ < Cl⁻ < F⁻ < OH⁻ < H₂O < NH₃ < en < CN⁻).
Write IUPAC names: [Co(en)₂Cl₂]⁺, K₃[Fe(CN)₆], [Pt(NH₃)₂Cl(NO₂)] etc. Find oxidation state. Nomenclature 2 marks 4+ times Linkage isomers (e.g., NO₂ vs ONO) repeated.
Why do transition metal complexes show color? Explain d-d transition in [Ti(H₂O)₆]³⁺. Case-based/Short 3-4 marks 3+ times Crystal field theory core.
Assertion-Reason: [Ni(CN)₄]²⁻ is diamagnetic while [NiCl₄]²⁻ is paramagnetic. Assertion-Reason 1 mark 3+ times (increased recently) dsp² (square planar) vs sp³ (tetrahedral).
Discuss biological importance of coordination compounds (e.g., haemoglobin, chlorophyll, vitamin B12). Short Answer 2-3 marks 2-3 times Fe²⁺/Fe³⁺ in haemoglobin, Co in B12.

📖 Best Updated Preparation Format (2026 Boards)

📋 Prioritization Order

  1. Coordination Compounds (highest marks & most conceptual)
  2. d- and f-Block Elements
  3. Then revise physical & organic chemistry

📚 Study Strategy

  • Master CFT diagrams (octahedral/tetrahedral splitting), hybridization table, spectrochemical series.
  • Practice 8-10 PYQs per topic from 2022-2025 (ignore pre-2022 if from deleted chapters).
  • Focus on assertion-reason, case-based, and numerical (magnetic moment).
  • Use NCERT examples + diagrams (label clearly in answers).

✍️ Answer Format Tips

  • Short answers: Definition → Example/Equation → Reason.
  • Draw & label splitting diagrams or orbital hybridization whenever asked.
  • For nomenclature: Follow IUPAC order strictly (ligands alphabetical, then metal).

⏰ Time Allocation in Exam

Inorganic now ~15 mins max (focus quality over quantity).

This guide is fully aligned with the latest 2025-26 syllabus. Focus on these two chapters and you'll cover the inorganic part solidly. Good luck with your preparation!