Explanation: The atom which defines the structure of a family of organic compounds and their properties is called a functional group. Functional groups are specific groups of atoms or bonds within molecules that are responsible for the characteristic chemical reactions of those molecules.

In S_N1 reaction, some of the substrate, even after ionisation, remains associated as an intimate ion pair preventing nucleophilic attacks from front side and gives inverted product.

Due to partial reaction of nucleophile with intimate ion pair, net inversion of configuration is observed although predominant reaction occurs at planar carbocation giving racemic products.

Tertiary halide would be most reactive in S_N1 reaction.

Tertiary halide would react at fastest rate with AgNO₃ as reaction will proceed by S_N1 mechanism.

Y forms a tertiary carbocation which rearranges to a further more stable benzylic carbocation.

Rate of S_N1 reaction is directly proportional to concentration of alkyl halide but independent of concentration of nucleophile. Non-polar solvents play no role in S_N1 reaction.

S_N1 reaction proceeds via carbocation intermediate which is being indicated here by two transition states and a small trough between reactant and product. Also the second transition state must be below first transition state in S_N1 reaction

Electron donating —CH₃ gro up stabilises benzylic carbocation, hence increases reactivity of corresponding substrate. Electron withdrawing —NO₂ decreases stability of carbocation, decreases reactivity of corresponding substrate in S_N1 reaction

It forms a secondary carbocation which, by hydride shift, rearranges to a tertiary carbocation.

Increasing temperature increases rate of any reaction. Also, rate of S_N1 reaction is directly proportional to concentration of alkyl halide but independent of nucleophile and aprotic solvent.

(III) forms tertiary carbocation, hence most reactive. (I) is least reactive as highly unstable carbocation is formed at bridge head carbon of bicyclic compound.

Protic solvents solvate carbocation, promotes S_N1 reaction.

(V) form s m ost stable, tertiary allylic, carbocation. (II) is vinylic halide, least reactive.

(II) is most reactive as it forms aromatic carbocation (III) is next most reactive as it forms allylic carbocation. (I) is least reactive as it forms least stable cyclopropyl carbocation.

(II) forms more stable carbocation than (I).

Both statements are true but the two different products are due to resonance in carbocation intermediate as