Which series is the most reactive series? alkyne alkene alkane methane

Hello.

Alkali metals are the most reactive group in the periodic table, not to be confused with Alkaline earth metals.

Also, Methane is a gas, not a group on the periodic table.

they contain triple bond, one sigma bond and 2 pi bonds. Pi bonds are weak and easily broken making the compound active. 

Chemical reaction is the process of breaking down bonds in reactants and forming new bonds in products. 
In Alkynes breaking down bonds is easier so they are more active.

Have a nice day