Answer: -
The mechanism for Br production from NBS is shown in the attached file.
N-bromo succinimide is a reagent used to brominate. It is most commonly used in allylic bromination, where a hydrogen on a carbon adjacent to a double bond is replaced.
It is selective in nature, unaffecting the normal double bond as compared to only bromine.
It also has a low concentration of bromine as an added advantage.
Answer:
Iron, copper , calcium
Explanation:
Iron , copper and calcium are present in three different groups.
Iron is present in group eight.
Copper is present in group eleven.
Calcium is present in group two.
Sodium , potassium and rubidium are present in same group i.e. group one. These are alkali metals.
Fluorine, chlorine and bromine are present in group seventeen. These are halogens.
Argon, Krypton and xenon are present in same group i.e, group eighteen. All are these noble gases.
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