# Which of these is not an isomer of (the straight-chained) "C"_6"H"_14 (hexane)?

Dec 30, 2016

#### Explanation:

All the molecules have the formula ${\text{C"_6"H}}_{14}$.

However, B is not an isomer of hexane.

That structure is hexane.

Dec 30, 2016

All isomers of one compound must have the same chemical formula. So, if it doesn't have 6 carbons and 14 hydrogens, it's out. Unfortunately, they all are valid under that condition.

The only differentiating factor then, is whether it is a different atomic connection with respect to:

${\text{H"_3"C"-"CH"_2-"CH"_2-"CH"_2-"CH"_2-"CH}}_{3}$

which is the straight-chained structure.

$\boldsymbol{B}$ is the one that is the straight-chained structure (rotate the right end ${90}^{\circ}$ counterclockwise), so it's not different from the original.

(It technically is an isomer, but it is not an isomer of itself. Not the best-worded question.)