Đáp án đúng: A
Giải chi tiết:\(\begin{array}{l}\,\,\,\,\,\,\,\,\,\,{C_n}{H_{2n + 1}}N{H_2}(X){C_n}{H_{2n + 1}}N{H_3}Cl\,(Y)AgCl\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,0,4\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,0,4\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \leftarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,0,4\,\,\,\,\,\,\,\,(mol)\\\overline {{M_Y}} = \frac{{34}}{{0,4}} = 85\, \Rightarrow n = 2,25 \Rightarrow X\left\{ \begin{array}{l}{C_2}{H_7}N\,\,\,x\,\,mol\\{C_3}{H_9}N\,\,\,y\,mol\end{array} \right.\,\\\left\{ \begin{array}{l}x + y = {n_X} = 0,4\\2x + 3y = 2,25.0,4 = {n_{C(X)}}\end{array} \right. \Rightarrow \left\{ \begin{array}{l}x = 0,3\\y = 0,1\end{array} \right.\\\Rightarrow \% {C_2}{H_7}N = \frac{{0,3.45}}{{0,3.45 + 0,1.59}}.100 = 69,59\% .\end{array}\)
Đáp án A