Consider the following alcohols:(I) C_6H_5CH_ | vedclass

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(A) The reaction of alcohols with $HBr$ proceeds via the formation of a carbocation intermediate. The rate of reaction is directly proportional to the

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$III > I > IV > II$

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(A) The reaction of alcohols with $HBr$ proceeds via the formation of a carbocation intermediate. The rate of reaction is directly proportional to the stability of the carbocation formed.$1$. The carbocations formed are substituted benzyl carbocations: $X-C_6H_4-CH_2^+$.$2$. Electron-donating groups $(EDG)$ increase the stability of the carbocation,while electron-withdrawing groups $(EWG)$ decrease it.$3$. The substituents are: - $CH_3O-$ (methoxy): Strong $+M$ effect (strongly stabilizing).- $H$ (hydrogen): Reference.- $Br$ (bromo): $-I$ effect (destabilizing).- $O_2N-$ (nitro): Strong $-M$ and $-I$ effects (strongly destabilizing).Thus,the stability order of the carbocations is: $III (methoxy) > I (H) > IV (bromo) > II (nitro)$.Therefore,the order of reactivity is $III > I > IV > II$.

Consider the following alcohols:
$(I)$ $C_6H_5CH_2OH$
$(II)$ $O_2N-C_6H_4-CH_2OH$ (para-nitro)
$(III)$ $CH_3O-C_6H_4-CH_2OH$ (para-methoxy)
$(IV)$ $Br-C_6H_4-CH_2OH$ (para-bromo)
The order of decreasing reactivities of these alcohols towards nucleophilic substitution with $HBr$ is:

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Consider the following alcohols:$(I)$ $C_6H_5CH_2OH$$(II)$ $O_2N-C_6H_4-CH_2OH$ (para-nitro)$(III)$ $CH_3O-C_6H_4-CH_2OH$ (para-methoxy)$(IV)$ $Br-C_6H_4-CH_2OH$ (para-bromo)The order of decreasing reactivities of these alcohols towards nucleophilic substitution with $HBr$ is: