Câu hỏi 29

\(\begin{array}{l}5,46g\,E\left\{ \begin{array}{l}{C_n}{H_{2n - 2}}:x\\{C_m}{H_{2m + 3}}N:y\end{array} \right. + {O_2}:0,495\,mol \to \left\{ \begin{array}{l}C{O_2}:a\\{H_2}O:a\\{N_2}\end{array} \right.\\BTNT\,oxi:2{n_{{O_2}}} = 2{n_{C{O_2}}} + {n_{{H_2}O}} \Rightarrow 0,495.2 = 2a + a \Rightarrow a = 0,33\,mol\\5,46 = {m_E} = {m_C} + {m_H} + {m_N} = 0,33.12 + 0,33.2 + {m_N}\\ \Rightarrow {m_N} = 0,84 \Rightarrow y = 0,06\,mol\\{n_{{H_2}O}} - {n_{C{O_2}}} = 0 \Rightarrow x = 1,5y = 0,09\,mol\\\left\{ \begin{array}{l}nx + my = {n_{C{O_2}}} = 0,33\\2 < n < 3\end{array} \right. \Rightarrow \left\{ \begin{array}{l}0,09n + 0,06m = 0,33\\2 < n < 3\end{array} \right.\\ \Rightarrow 1 < m < 2,5 \Rightarrow n = 2 \Rightarrow A\min :\,{C_2}{H_7}N\end{array}\)

Đáp án A