Câu hỏi 27

\(\begin{array}{l}
X:{\rm{ }}{C_n}{H_{2n + 3}}N.\,\,\,\,\,\,\,\% N = \frac{{14}}{{14n + 17}}.100 \Rightarrow n = (\frac{{1400}}{{\% N}} - 17):14\\
{X_1}:\% N = 31,11\% \Rightarrow {n_1} = (\frac{{1400}}{{31,11}} - 17):14 = 2 \Rightarrow {X_1}:{C_2}{H_7}N\\
{X_2}:\% N = 23,73\% \Rightarrow {n_2} = 3 \Rightarrow {X_2}:{C_3}{H_9}N\\
{X_3}:\% N = 16,09\% \Rightarrow {X_3}:{C_5}{H_{13}}N\\
{X_4}:\% N = 13,86\% \Rightarrow {X_4}:{C_6}{H_{15}}N\\
mgX\left\{ \begin{array}{l}
{C_2}{H_7}N\,x\,mol\\
{C_3}{H_9}N\,3x\,mol\\
{C_5}{H_{13}}N\,7x\,mol\\
{C_6}{H_{15}}N\,9x\,mol
\end{array} \right. + HCl \to 296,4g\,muoi\\
{n_{HCl(pu)}} = x + 3x + 7x + 9x = 20x\,mol\\
\left\{ \begin{array}{l}
m = 45x + 59.3x + 87.7x + 101.9x\\
m + 20x.36,5 = 296,4\,\,(BTKL)
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
m = 208,8\\
x = 0,12
\end{array} \right.
\end{array}\)

Đáp án B