Hỗn hợp A gồm ba chất hữu cơ X, Y, Z đơn chức đồng phân của nhau, đều tác dụng được với NaOH

\({n_X} = \frac{{P.V}}{{R.T}} = \frac{{1.2,1}}{{0,082.(273 + 136,5)}} = 0,0625\,\,(mol)\)

\({m_X} = \frac{{4,625}}{{0,0625}} = 74\)

X, Y, Z đơn chức tác dụng với NaOH   ⇒  X, Y, Z là axit hoặc este.

=> CTPT có dạng: C_xH_yO₂

=> 12x +  y  + 32 = 74

=> 12x + y =42

=> x = 3; y =6

\(A:\,\,\,\,13,875\,\,\,\,(g)\left\{ \begin{array}{l} HCOO{C_2}{H_5}\,\,\,\,a\,\,(mol)\\ \\ C{H_3}{\rm{COO}}C{H_3}\,\,\,b\,\,(mol)\\ \\ {C_2}{H_5}{\rm{COO}}H\,\,\,\,\,\,c\,\,\,(mol) \end{array} \overset{NaOH}{\rightarrow}\right.\,\,\,\,\,\,\,\,\left\{ \begin{array}{l} HCOONa\,\,\,\,\,\, + \,\,\,{C_2}{H_5}OH\\ \,\,\,\,\,\,a\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,a\\ C{H_3}{\rm{COO}}Na\,\,\,\,\,\, + \,\,\,C{H_3}OH\\ \,\,\,\,\,\,\,\,b\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,b\,\\ \,\,\,\,{C_2}{H_5}{\rm{COO}}Na\,\,\,\,\, + \,\,{H_2}O\\ \,\,\,\,\,\,\,\,\,\,\,c\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,c\, \end{array} \right.\)

\(\Rightarrow \left\{ \begin{array}{l} a + b + c = \frac{{13,875}}{{74}} = 0,1875\\ 68a + 82b + 96c = 15,375\\ {d_{acol/{H_2}}} = \frac{{46a + 32b}}{{(a + b).2}} = 20,67 \end{array} \right.\)

\(\Rightarrow \left\{ \begin{array}{l} a = 0,075\\ b = 0,0375\\ n = 0,075 \end{array} \right.\)

X, Y, Z cùng CTPT.

=> %m = %n

=> 40% ; 20% ; 40%.