Rate of $S_N2$ reactions depends on :

The product $A$ of the following sequence of reactions is:
Ethylbenzene $\xrightarrow[(b) Cl_2, \Delta]{(a) Br_2, Fe}$ $\xrightarrow{(c) alc. KOH} 'A' \text{ (Major product)}$

Among the following compounds $I-IV$,which one forms a yellow precipitate on reacting sequentially with $(i)$ $NaOH$,$(ii)$ dil. $HNO_{3}$,and $(iii)$ $AgNO_{3}$?

The reaction of one mole of $3-$chlorohexane with one mole of $NaI$ in the presence of acetone yields which of the following as the major product?

The $Wurtz-Fittig$ reaction involves the condensation of:

Correct order of nucleophilicity for $S_N2$ reaction