To form alkane isonitrile, alkyl halide is reacted with:

For the reaction, 

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}+\mathrm{HX}\stackrel{{\mathrm{ZnX}}_2}{⟶}{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{X},$ the order of reactivity is:

Butanenitrile may be prepared by heating:

An alkyl halide may be converted into an alcohol by _____.