Haloalkanes and Haloarenes

goals
List the following compounds in order of decreasing reactivity toward ${CH}_{3}O$ in an ${S}_{N}2$ reaction carried out in ${CH}_{3}OH$; ${CH}_{3}F$, ${CH}_{3}Cl$, ${CH}_{3}Br$, ${CH}_{3}I$, ${CH}_{3}O{SO}_{2}{CF}_{3}$, $_{ }^{ 14 }{ { CH }_{ 3 } }OH$
The maximum  rate of $Sn2$ is :
Write the stereochemical products formed in the given elimination reaction.
The reaction conditions leading to the best yield of $C_{2}H_{5}Cl$ are:
Assertion: Chloroform gives chloropicrin with $HNO_{3}$ vapour.
Reason: Chloropicrin is used as an insecticide.