Which one of the following forms propane nitrile as the major product?

Which of the following is the most reactive towards $S_{N}1$ mechanism?

The major product in the given reaction is:

Predict the order of reactivity of the following compounds in $S_{N}1$ and $S_{N}2$ reactions:
$(i)$ The four isomeric bromobutanes
$(ii)$ $C_{6}H_{5}CH_{2}Br$,$C_{6}H_{5}CH(C_{6}H_{5})Br$,$C_{6}H_{5}CH(CH_{3})Br$,$C_{6}H_{5}C(CH_{3})(C_{6}H_{5})Br$

Among $CH_3F$,$CH_3Cl$,$CH_3Br$,and $CH_3I$,which one does not give methane on reduction?

What would be the product formed when $1-Bromo-3-chloro$ cyclobutane reacts with two equivalents of metallic sodium in ether?