E₂ reactions are:

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This question was previously asked in

DSSSB PGT Chemistry (Female) Official Paper (Held On: 06 Jul, 2018 Shift 1)

Answer 1

CONCEPT:

E2 Reaction Characteristics

E2 (Elimination, bimolecular) reactions occur in a single step where a base abstracts a proton while the leaving group simultaneously departs.
These reactions are influenced by the stereochemistry of the substrate and often involve specific spatial arrangements.
E2 reactions typically follow an anti-periplanar geometry where the proton and leaving group are opposite to each other in the same plane.

EXPLANATION:
Stereoselective-and-stereospecific-E2-elimination-based-on-beta-hydrogen

E2 reactions are stereoselective, meaning they favor the formation of a specific stereoisomer over others based on the spatial arrangement of the reacting atoms.
They are also anti-eliminations, as the hydrogen atom being abstracted and the leaving group are positioned opposite to each other (anti-periplanar) in the same plane.
Syn elimination (where the hydrogen and leaving group are on the same side) is not favored in E2 reactions due to steric and electronic factors.
Stereo specificity refers to the reaction proceeding in a way that leads to a specific stereochemical configuration of the product, but this is not a defining characteristic of E2 reactions in general.

Therefore, E2 reactions are stereoselective and anti-eliminations.