$C_8H_{18}$ có 18 đồng phân
1) $CH_3-C(CH_3)_2-C(CH_3)_2-CH_3$
$\text{2,2,3,3-Tetramethylbutan}$
2) $CH_3-C(CH_3)_2-CH(CH_3)-CH_2-CH_3$
$\text{2,2,3-Trimethylpentan}$
3) $CH_3-C(CH_3)_2-CH_2-CH(CH_3)-CH_3$
$\text{2,2,4-Trimethylpentan}$
4) $CH_3-C(CH_3)_2-CH_2-CH_2-CH_2-CH_3$
$\text{2,2-Đimethylhenxan}$
5) $CH_3-CH(CH_3)-C(CH_3)_2-CH_2-CH_3$
$\text{2,3,3-Trimethylpentan}$
6) $CH_3-CH(CH_3)-CH(CH_3)-CH(CH_3)-CH_3$
$\text{2,3,4-Trimethylpentan}$
7) $CH_3-CH(CH_3)-CH(CH_3)-CH_2-CH_2-CH_3$
$\text{2,3-Đimethylhenxan}$
8) $CH_3-CH(CH_3)-CH_2-CH(CH_3)-CH_2-CH_3$
$\text{2,4-Đimethylhenxan}$
9) $CH_3-CH(CH_3)-CH_2-CH_2-CH(CH_3)-CH_3$
$\text{2,5-Đimethylhenxan}$
10) $CH_3-CH(CH_3)-CH(C_2H_5)-CH_2-CH_3$
$\text{2-Methyl-3-ethylpentan}$
11) $CH_3-CH(CH_3)-CH_2-CH_2-CH_2-CH_2-CH_3$
$\text{2-Methylheptan}$
12) $CH_3-CH_2-C(CH_3)_2-CH_2-CH_2-CH_3$
$\text{3,3-Dimethylhexan}$
13) $CH_3-CH_2-CH(CH_3)-CH(CH_3)-CH_2-CH_3$
$\text{3,4-Dimethylhexan}$
14) $CH_3-CH_2-CH(C_2H_5)-CH_2-CH_2-CH_3$
$\text{3-Ethylhexan}$
15) $CH_3-CH_2-C(CH_3)(C_2H_5)-CH_2-CH_3$
$\text{3-Methyl-3-ethylpentan}$
16) $CH_3-CH_2-CH(CH_3)-CH_2-CH_2-CH_2-CH_3$
$\text{3-Methylheptan}$
17) $CH_3-CH_2-CH_2-CH(CH_3)-CH_2-CH_2-CH_3$
$\text{4-Methylheptan}$
18) $CH_3-CH_2-CH_2-CH_2-CH_2-CH_2-CH_2-CH_3$
$\text{n-octan}$
