To obtain R-I from R-Cl

To obtain Ar-X by replacing diazo group of $\text{AR-N}_2^+\text{-X}^-$ using $\text{CuCl}$ / $\text{HCl}$

To obtain R-F from R-Cl using AgF

To obtain $\text{R-CH}_2\text{-R}$ from R-CO-R using Zn-Hg / HCl

Strong nucleophile

Non - Polar solvent

Bulky alkyl groups on the carbon atom attached to halogen atom

Small alkyl groups on the carbon atom attached to halogen atom

$2$

$3$

$4$

$6$

$3^\circ > 1^\circ > 2^\circ$

$3^\circ > 2^\circ > 1^\circ$

$1^\circ > 2^\circ > 3^\circ$

$1^\circ > 3^\circ > 2^\circ$