Em tham khảo nha:
\(\begin{array}{l}
a)\\
CTHH:{C_x}{H_y}\\
{M_{{C_x}{H_y}}} = 29 \times 2 = 58\,dvC\\
{m_C} = 58 \times 82,76\% = 48g\\
{m_H} = 58 - 48 = 10g\\
{n_C} = \dfrac{{48}}{{12}} = 4\,mol\\
{n_H} = \dfrac{{10}}{1} = 10\,mol\\
x:y = {n_C}:{n_H} = 4:10\\
\Rightarrow CTHH:{C_4}{H_{10}}\\
b)\\
CTHH:{C_x}{H_y}\\
{M_{{C_x}{H_y}}} = 15 \times 2 = 30\,dvC\\
{m_C} = 30 \times 80\% = 24g\\
{m_H} = 30 - 24 = 6g\\
{n_C} = \dfrac{{24}}{{12}} = 2\,mol\\
{n_H} = \dfrac{6}{1} = 6\,mol\\
x:y = {n_C}:{n_H} = 2:6\\
\Rightarrow CTHH:{C_2}{H_6}
\end{array}\)
