PYQ Theme 1 — Predict spin state and μ from ligand (Most Frequent): The single most frequent question type: given a complex with a specific ligand, predict whether it is diamagnetic or paramagnetic, and calculate μ. Protocol: (1) identify metal oxidation state and d-electron count; (2) locate the ligand on the spectrochemical series; (3) decide low spin (strong field, $\Delta o$ > P) or high spin (weak field, $\Delta o$ < P); (4) fill d-orbitals accordingly; (5) count unpaired electrons; (6) apply μ = √(n(n+2)) BM. Classic example: [Co($NH_{3}$){6}]^{3+} — $Co^{3+}$ is $d^{6}$, $NH_{3}$ is strong field → low spin → t{2}$g^{6}$ $eg^{0}$ → 0 unpaired → μ = 0, diamagnetic.

PYQ Theme 2 — $KMnO_{4}$ colour and product in specified medium: Questions give a medium (acidic, neutral, or basic) and ask for the product's colour or the number of electrons transferred. Memorise: acid = colourless $Mn^{2+}$ (5$e^{-}$); neutral = brown $MnO_{2}$ (3$e^{-}$); basic = green $MnO_{4}^{2-}$ (1$e^{-}$).

PYQ Theme 3 — IUPAC name from formula: Steps: list all ligands, sort alphabetically, name anionic ligands with -o suffix, name neutral ligands with special names (aqua, ammine, carbonyl, nitrosyl), add metal name with Roman numeral oxidation state, name the outer ion last. Frequently tested: [Co($NH_{3}$)_{4}$Cl_{2}$]Cl → tetraamminedichloridocobalt(III) chloride.

PYQ Theme 4 — Isomerism identification: Given two formulas, identify the type of isomerism. Key triggers: $MA_{2}B_{2}$ square planar → geometrical; ambidentate ligand appears → linkage; same formula, different counter-ions in solution → ionisation; tris-chelate complex with no plane of symmetry → optical.

PYQ Theme 5 — Lanthanoid contraction consequence: Why are Zr and Hf nearly identical in properties? Answer: lanthanoid contraction — the 14 lanthanoids from La to Lu contract the 5d orbitals of Period 6 elements to match the 4d orbital sizes of Period 5 elements.