Em tham khảo nha:

\(\begin{array}{l}
2)\\
{n_{C{O_2}}} = \dfrac{{4,4}}{{44}} = 0,1\,mol\\
{n_{{H_2}O}} = \dfrac{{2,7}}{{18}} = 0,15\,mol\\
{n_C} = {n_{C{O_2}}} = 0,1\,mol\\
{n_H} = 2{n_{{H_2}O}} = 0,3\,mol\\
{m_O} = 2,3 - 1,2 - 0,3 = 0,8g\\
{n_O} = \dfrac{{0,8}}{{16}} = 0,05\,mol\\
{n_C}:{n_H}:{n_O} = 0,1:0,3:0,05 = 2:6:1\\
 \Rightarrow CTDGN:{C_2}{H_6}O\\
CTPT:{({C_2}{H_6}O)_n}\\
{M_A} = 46g/mol \Rightarrow 46n = 46 \Rightarrow n = 1\\
CTPT:{C_2}{H_6}O\\
3)\\
a)\\
{n_{C{O_2}}} = \dfrac{{26,4}}{{44}} = 0,6\,mol\\
{n_{{H_2}O}} = \dfrac{{10,8}}{{18}} = 0,6\,mol\\
{n_{{O_2}}} = \dfrac{{19,2}}{{32}} = 0,6\,mol\\
{n_C} = {n_{C{O_2}}} = 0,6\,mol\\
{n_H} = 2{n_{{H_2}O}} = 1,2\,mol\\
BTNT:{n_O} + 2{n_{{O_2}}} = 2{n_{C{O_2}}} + {n_{{H_2}O}}\\
 \Rightarrow {n_O} = 0,6 \times 2 + 0,6 - 0,6 \times 2 = 0,6\,mol\\
{n_C}:{n_H}:{n_O} = 0,6:1,2:0,6 = 1:2:1\\
 \Rightarrow CTDGN:C{H_2}O\\
CTPT:{(C{H_2}O)_n}\\
170 < {M_A} < 190 \Rightarrow 170 < 30n < 190\\
 \Rightarrow n = 6\\
CTPT:{C_6}{H_{12}}{O_6}
\end{array}\)