IUPAC name of

${\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{CH}-{\mathrm{CH}}_3$ is

                         ${\mathrm{H}}_3\mathrm{C}-\stackrel{|}{\mathrm{C}}\mathrm{H}-{\mathrm{CH}}_3$

 

Longest chain rule: The first step in naming an organic compound is to select the longest continuous chain of carbon atoms which mayor may not be horizontal.The horizontal chain consists 5 carbon atoms while the longest zig-zag chain consists 6 carbon atoms. It is, thus, derivative of hexane.