An aqueous solution of sodium or potassium salt of carboxylic acid is electrolysed in this reaction, resulting in the dissociation of the salt into a carboxylate ion and sodium or potassium ions. 

The total number of different alkanes are formed when the following mixture is subjected to electrolysis:

${\mathrm{CH}}_3{\mathrm{COONa}}_{\left(\mathrm{aq}\right)} \mathrm{and} {\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{COONa}}_{\left(\mathrm{aq}\right)}$ 

In this ethane, butane and propane are formed.

${\mathrm{CH}}_3\mathrm{COONa}\to \stackrel{\bullet }{\mathrm{C}}{\mathrm{H}}_3$

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{COONa}\to {\stackrel{\bullet }{\mathrm{C}}}_2{\mathrm{H}}_5$

$2{\stackrel{\bullet }{\mathrm{C}}}_2{\mathrm{H}}_5\to {\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3$

$2\mathrm{C}{\stackrel{\bullet }{\mathrm{H}}}_3\to {\mathrm{CH}}_3-{\mathrm{CH}}_3$

$\stackrel{\bullet }{\mathrm{C}}{\mathrm{H}}_3+{\stackrel{\bullet }{\mathrm{C}}}_2{\mathrm{H}}_5\to {\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_3$

So, the total number of alkanes formed here will be $3$