The addition mechanism of 4 1. aldehyde, ketone and 2,4-dinitrophenylhydrazine belongs to (b) A. electrophilic addition B. nucleophilic addition C. free radical reaction D. synergistic reaction 42. Among the following compounds, (a) benzaldehyde B. ethanol C. acetone D. acetoacetic acid 43. Among the following compounds, the most acidic one is (c) A, formic acid b, acetic acid c, oxalic acid d, propionic acid 44. The following compounds are unstable to heat and can be easily dehydrated to form cyclic lactone (D) A. α- hydroxy acid B. β- hydroxy acid C. β- keto acid D .γ- hydroxy acid 45. Among the following compounds, (a) A.C6H5NH2B. (CH3) 2NHC. NH3·d .(CH3)4N+OH-46。 Which of the following can be used? Triethylamine (A) A nitrite B. PH test paper C hydrochloric acid D sodium hydroxide 47. Among the following compounds, (D) A. C6H5NH2 B. (CH3) is the most alkaline. 2NH2C。 NH3·d .(CH3)4N+OH-49。 There is no () a. glycerol b. higher fatty acid c. choline 50 in the product of complete hydrolysis of cephalin. The ones that can react with Torun reagent are (c) A. Cholesterol B. Cholic acid C. Aldosterone D. Testosterone 5 1. The product of complete hydrolysis of lecithin. Glycerol B. Higher fatty acid C. Choline 52. The basic structural unit of amylopectin is D- glucose, and the glycosidic bonds connecting the glucose units are () A. α- 1, 4 B. α- 1, 4 and α- 1, 6 c.α-65438.