Question

How many structural isomers can you draw for pentane?

• A. $2$
• B. $4$
• C. $3$
• D. $6$

Answer 1

The correct option is C

$3$

The correct option is option C

The explanation for the correct option.

• Structural isomers are molecules with the same chemical formula but different atomic arrangements and bonding patterns.
• Pentane is an organic compound with five carbons, and since it ends in -ane, we can conclude that there are only single bonds in it (it is a saturated molecule).
• It has a molecular formula ${\mathrm{C}}_5{\mathrm{H}}_{12}$
• Pentane exists in three structural isomers: n-pentane, isopentane, and neopentane.
• In n-pentane or pentane the five carbon atoms are organized in a straight chain, without any branching.
• Isopentane or $2-$methyl butane: In this isomer, the first four carbon atoms are organized in a straight chain, and the fifth carbon atom is joined to the second carbon atom of the straight chain to form a branch.
• Neopentane or $2,2-$dimethylpropane in this isomer the three carbon atoms are grouped in a sequence to form a straight chain, and the additional two carbon atoms are joined to the middle carbon atom to produce two branches.

Final answer: There are three structural isomers present for pentane.