a,
Gọi CTPT phenol là $C_nH_{2n-6}O$ ($n\ge 6$)
$\%m_O=13,144\%$
$\Rightarrow \dfrac{16.100}{14n-6+16}=13,144$
$\Leftrightarrow n=8$
Vậy CTPT phenol là $C_8H_{10}O$
b,
Tên gọi:
(1) 2-etylphenol
(2) 3-etylphenol
(3) 4-etylphenol
(4) 2,3-đimetylphenol
(5) 3,4-đimetylphenol
(6) 2,6-đimetylphenol
(7) 2,4-đimetylphenol
(8) 3,5-đimetylphenol
(9) 2,5-đimetylphenol