Question

How many structural isomers does butane have?

Answer 1

Butane has just two structural isomers: i-butane and n-butane.

Explanation:

n-butane, normal butane, `C_4H_10`
The first one is the normal,unbranched butane. We add the prefix "n-" to the main name "butane".

Lewis structure:

Skeletal diagram:

i-butane, isobutane, `C_4H_10`
The second one is isobutane, "branched" butane. We add the prefix "i-" to the main name. The second name for i-butane is
2-methylpropane