Giá trị của m là

Đáp án đúng là: B

 $\mathrm{m}\left(\mathrm{g}\right)\left\{\begin{array}{l}{\mathrm{CH}}_3\mathrm{CHO}:\mathrm{x}\mathrm{mol}\\ {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{CHO}:\mathrm{y}\mathrm{mol}\end{array}\right.\stackrel{\left[\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_2\right]\mathrm{OH}}{\to }\underset{17,5\mathrm{gam}}{\underbracket{\left\{\begin{array}{l}{\mathrm{CH}}_3{\mathrm{COONH}}_4:\mathrm{x}\mathrm{mol}\\ {\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{COONH}}_4:\mathrm{y}\mathrm{mol}\end{array}\right.}}+\underset{0,4\mathrm{mol}}{\underbracket{2\mathrm{Ag}}}$

\[ \Rightarrow \left\{ \begin{array}{l}{m_{muoi}} = 77x + 91y = 17,5\\{n_{Ag}} = 2x + 2y = 0,4\end{array} \right.\, \Rightarrow \left\{ \begin{array}{l}x = 0,05\,mol\\y = 0,15\,mol\end{array} \right.\, \Rightarrow \,m = {m_{aldehyde}} = 10,9\,g.\]