The Grignard reagent can be prepared by using magnesium in dry ether on
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \(C_2H_5Br\)
Grignard reagents, RMgX, are alkyl magnesium halides. They are made by the reaction of a haloalkane with magnesium metal in dry ether; the magnesium inserts itself into the carbon–halogen bond:
\( \displaystyle \ce{C2H5Br + Mg} \xrightarrow{\text{dry ether}} \ce{C2H5MgBr} \)
The ether must be dry because Grignard reagents react at once with any source of protons, including water: \( \ce{C2H5MgBr + H2O -> C2H6 + Mg(OH)Br} \). So of the given compounds only bromoethane forms the reagent.
Why the other options are incorrect
Option (1) \(C_2H_5OH\) — Incorrect. Ethanol has an acidic O–H hydrogen; it would destroy a Grignard reagent (giving ethane), not form one.
Option (3) \(C_2H_6\) — Incorrect. Ethane has no carbon–halogen bond for the magnesium to insert into; alkanes do not react with Mg.
Option (4) \(C_2H_5NO_2\) — Incorrect. Nitroethane has no halogen, and its nitro group would react with a Grignard reagent instead of forming one.
NCERT (2026-27 edition):
Reaction with Metals
