(A) In Anionic polymerization chain terminating step is absent.
(R) Anionic polymerization is initiated by NaNH₂.

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Both (A) and (R) are true and (R) is the correct explanation of (A)

Both (A) and (R) are true but (R) is not the correct explanation of (A)

(A) is true but (R) is false

Both (A) and (R) are false

answer is B.

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Detailed Solution

Anionic polymerization is a type of polymerization reaction that involves the initiation of polymerization by a strong base or a strong nucleophile.
In this type of polymerization, the polymer chain grows by the addition of monomers to the active center, which is usually a negatively charged species, such as a carbanion or an alkoxide ion.
In anionic polymerization, the chain terminating step is absent because the active center remains negatively charged and can continue to add monomers until all of the monomers are consumed or until the reaction is quenched by a proton source or other termination agent.
This results in a high molecular weight polymer with a narrow molecular weight distribution.
Anionic initiators for polymerization typically include alkali metals such as sodium or potassium, alkali metal amides such as sodium amide (NaNH₂), or alkyl lithium compounds such as n-butyllithium (n-BuLi).
These initiators are used to generate anions that can initiate the polymerization reaction by attacking a monomer molecule and forming a reactive intermediate that can then propagate the polymer chain.
So, both (A) and (R) are true but (R) is not the correct explanation of (A).

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