💯 Elimination vs Substitution Revision Q&A (Class 12 Chemistry) Q: What is a substitution reaction ? A: A reaction where an atom/group in a molecule is replaced by another atom/group. Q: What is an elimination reaction ? A: A reaction where atoms/groups are removed from a molecule to form a multiple bond. Q: Which reagents favor substitution over elimination? A: Weak bases and strong nucleophiles favor substitution. Q: Which reagents favor elimination over substitution? A: Strong bulky bases favor elimination. Q: What is the leaving group in substitution/elimination reactions? A: Usually a halide ion (-X). Q: What is the difference between SN1 and SN2 mechanisms? A: SN1 is unimolecular with carbocation intermediate; SN2 is bimolecular and concerted . Q: What is the difference between E1 and E2 mechanisms? A: E1 has carbocation intermediate; E2 is concerted with base abstracting proton and leaving group leaving simultaneously. ...

25 short question-answer  on Haloalkanes : Basic Concepts What are haloalkanes? → Organic compounds containing a halogen (X = F, Cl, Br, I) attached to an alkyl group. How are haloalkanes classified? → Based on the carbon to which halogen is attached: Primary (1°): R-CH₂-X Secondary (2°): R₂-CH-X Tertiary (3°): R₃-C-X Which is more reactive: alkyl halides or aryl halides? → Alkyl halides, because aryl halides have resonance stabilization. Which is the best leaving group among halogens? → I⁻ (Iodide) because it is the largest and weakest base. Why do haloalkanes have higher boiling points than alkanes? → Due to dipole-dipole interactions and van der Waals forces. Preparation of Haloalkanes How is chloromethane prepared from methane? → By free radical halogenation: CH₄ + Cl₂ → CH₃Cl + HCl (in sunlight) How can alcohols be converted to haloalkanes? → By using: HCl, HBr, or HI PCl₅, PCl₃, SOCl₂ (best method for Cl) What is the best me...