A GRIGNARD REAGENT is formed by reacting an alkyl halide with

1. NCERT §6.5 (Reactions): a Grignard reagent has the general formula $\mathrm{R{-}MgX}$ (alkyl magnesium halide). 2. Preparation: $\mathrm{R{-}X} + \mathrm{Mg} \xrightarrow{\text{dry ether}} \mathrm{R{-}MgX}$. 3. The dry ether is CRUCIAL — moisture would destroy the Grignard. Ether also stabilises the organo-magnesium species through Lewis-base coordination. 4. Grignard reagents are extremely useful — they add to carbonyl compounds to give alcohols of arbitrary length, used in countless syntheses. 5. Option A is the Wurtz reaction (gives a coupled alkane, not a Grignard). Option C is for organozinc (Reformatsky reagent). Option D is for the Birch reduction conditions, not Grignard. _Source: NCERT Class 12 Chemistry Part 2, Ch 6, §6.5 (Grignard reagent preparation), p. 14–15._