Cho các chất sau: CH3-CH2-CHO (1), CH2=CH-CHO (2), CH3CHO (3), CH2=CH-CH2OH (4)

Câu hỏi :

Cho các chất sau: $$\begin{gathered} C{H}_3-C{H}_2-CHO\left(1\right), C{H}_2=CH-CHO\left(2\right), \\ C{H}_{3}CHO\left(3\right), C{H}_2=CH-C{H}_{2}OH\left(4\right), \\ C{H}_2=CH-CHO \left(5\right) \end{gathered}$$