The type of reactions that alkanes undergo is A) electrophilic substitution reactions. B) electrophilic addition reactions. C) free radical substitution reactions. D) free radical addition reactions. E) nucleophilic substitution reactions.

FREE RADICAL SUBSTITUTION REACTIONS

Explanation:

Alkanes undergo substitution reactions with halogens in the presence of ultra-violent light. In substitution reaction, an atom is exchanged with another atom. For exmaple, methane, an alkane reacts with bromine or chlorine( halogens) to form methylbromine or methylchlorine and hydrogen bromide or hydrogen chloride.

This type of substitution reaction is a free radical substitution reaction. In free radical substitution reaction, free radicals are the reactive intermediates and involves two or more steps as the case may be.

The initiation step where the free radicals are produced by homolysis  either by heat or ultra-violent ray of light. The free radicals produced are exchanged at the termination step as the produced free radicals recombines with another radical species of the reacting substances.

Methane + Bromine > Methylbromine + Hydrogen Bromide

CH4 + Br2 → CH3Br + HBr

You can see there is an exchange of a bromine atom with one hydrogen of methane that is one hydrogen atom in methane  is replaced by a bromine atom.

c is the answer because when something is left after something evaporates that shows the chemical change.