JEE Chemistry — Complete Formula Sheet

Whenever a numerical gives mass, volume, AND concentration together, convert everything to moles FIRST before doing any stoichiometric ratio work — mixing units mid-calculation is the #1 source of wrong answers here.

For electronic configuration exceptions (like Cr and Cu), just memorise the two famous exceptions directly — [Ar]3d⁵4s¹ and [Ar]3d¹⁰4s¹ — rather than trying to re-derive stability logic every time under exam pressure.

To quickly predict molecular geometry, count the steric number (bonded atoms + lone pairs) around the central atom FIRST — this single number directly tells you the hybridisation and base VSEPR shape before considering distortions.

For Graham's law problems, remember the ratio is INVERSE to the square root of molar mass — the lighter gas always diffuses/effuses faster, a quick sanity check before finalising your answer.

For spontaneity questions, build a quick sign table in your head: ΔH negative + ΔS positive = always spontaneous; ΔH positive + ΔS negative = never spontaneous; mixed signs depend on temperature — this covers every JEE spontaneity question type.

Whenever a buffer solution question appears, go straight to the Henderson-Hasselbalch equation instead of setting up a full ICE table — it's specifically built for buffer pH calculations and saves significant time.

Remember 'Reduction happens at Cathode, Oxidation happens at Anode' (RedCat, AnOx) for BOTH galvanic and electrolytic cells — the electrode names never swap, only the electron flow direction and cell type change.

Order of reaction must always be determined EXPERIMENTALLY from rate data, never assumed from the stoichiometric coefficients of the balanced equation — this distinction is one of the most frequently tested JEE concepts in kinetics.

Always include the van't Hoff factor 'i' for ionic solutes (i>1 for dissociation, i<1 for association like dimerisation) — forgetting 'i' for salts like NaCl or CaCl2 is the single most common calculation error in this chapter.

Memorise the number of atoms per unit cell for each lattice type directly — Simple Cubic Z=1, BCC Z=2, FCC Z=4 — since nearly every density/packing question starts by needing this Z value first.

Whenever you see an 'exception' question (like O having lower first ionisation energy than N), think about extra electron-electron repulsion in a half-filled/fully-filled stable subshell — most periodic trend exceptions trace back to this one idea.

For transition metal colour and magnetic property questions, always count unpaired d-electrons FIRST — unpaired electrons cause both paramagnetism and, combined with d-d transitions, the characteristic colours of transition metal compounds.

When comparing stability of carbocations/free radicals/carbanions, apply the effects in this priority order: resonance > hyperconjugation > inductive effect — this ranking resolves most 'which is more stable' JEE questions instantly.

The peroxide effect (anti-Markovnikov) applies ONLY to HBr, never to HCl or HI — this is one of the most specific, frequently tested exceptions in the entire hydrocarbons chapter.

To decide between SN1 and SN2 quickly, check the substrate type first — 1° substrates strongly favour SN2 (steric access), 3° substrates strongly favour SN1 (stable carbocation) — 2° substrates depend on the solvent and nucleophile strength.

To predict if a compound can undergo Aldol condensation, always check for the presence of an α-hydrogen FIRST — no α-hydrogen (like in benzaldehyde) means no self-Aldol, but it CAN undergo Cannizzaro reaction instead.

For amine basicity questions, always check whether the question specifies gas phase or aqueous (solution) phase — the basicity ORDER genuinely changes between the two due to solvation effects, a frequently tested JEE Advanced trap.

To classify a polymer quickly, check if a small molecule (like water) is released during formation — condensation polymerisation releases a byproduct, addition polymerisation does not, this single check resolves most classification questions.