The correct order of reactivity of the following benzyl halides towards reaction with $KCN$ is:

Which is the correct reactivity order for $E_2$ reaction with alcoholic $KOH$?

Which of the following compounds will produce the product shown in the image upon reaction with $NaCN$ via an $S_N2$ mechanism?

Which of the following expressions is representative of the rate law for a $S_{N}2$ reaction?

For the reactions given below:
$(I)$ Cyclohexyl chloride $\rightarrow$ Cyclohexyl cation + $Cl^-$,$\Delta H_1^{\circ}$
$(II)$ Cyclohex$-2-$enyl chloride $\rightarrow$ Cyclohex$-2-$enyl cation + $Cl^-$,$\Delta H_2^{\circ}$
$(III)$ Benzyl chloride $\rightarrow$ Benzyl cation + $Cl^-$,$\Delta H_3^{\circ}$
$(IV)$ Chlorobenzene $\rightarrow$ Phenyl cation + $Cl^-$,$\Delta H_4^{\circ}$
The correct decreasing order of enthalpies of reaction for producing the carbocation is:

Among the following,the most reactive towards alcoholic $KOH$ is: