Este: $C_nH_{2n}O_2$
$\Rightarrow \dfrac{2n.100}{14n+32}=9,8$
$\Leftrightarrow n=5(C_5H_{10}O_2)$
Đồng phân:
(1) $HCOO-CH_2-CH_2-CH_2-CH_3$
(2) $HCOO-CH_2-CH(CH_3)-CH_3$
(3) $HCOO-CH(CH_3)-CH_2-CH_3$
(4) $HCOO-C(CH_3)_2-CH_3$
(5) $CH_3COO-CH_2-CH_2-CH_3$
(6) $CH_3COOCH(CH_3)-CH_3$
(7) $C_2H_5COOC_2H_5$
(8) $CH_3-CH_2-CH_2COOCH_3$
(9) $CH_3-CH(CH_3)-COOCH_3$