$word_{count}$: 200

Common JEE question types: (1) Identify mechanism from substrate + reagent + conditions. (2) Predict product with correct stereochemistry. (3) Rank reactivity of substrates for SN1 or SN2. (4) Identify major product from competing pathways.

Quick decision checklist: Is substrate 3 degree? → with base: E2 only; without: SN1+E1. Is substrate methyl/1 degree? → strong Nu + aprotic: SN2; bulky base: E2. Is substrate 2 degree? → most complex case; consider all factors. Is substrate vinyl/aryl? → normally unreactive; look for SNAr or benzyne conditions.

Watch for traps: (1) Neopentyl = "primary" but acts like tertiary in SN2. (2) Rearranged products = $\frac{SN1}{E1}$ (never SN2). (3) In SNAr, F is best LG (opposite of normal). (4) Optical purity less than 100% in substitution → mixed SN1+SN2. (5) Stereochemistry: inversion = SN2; racemization = SN1. (6) anti-periplanar geometry locks which E2 product forms from cyclic substrates.

Time-saving: Draw Newman projection for E2 to quickly identify anti-periplanar H. Use the 3-step framework mechanically.