... dch cn cú nng phn trm l A 72,57% B 70,57% C 75,57% D 68,57% Cõu 19: Ancol X mch h cú s nguyờn t cacbon bng s nhúm chc Cho 9,3 gam ancol X tỏc dng vi Na d thu c 3,36 lớt khớ Cụng thc cu to thu ... l A CH3OH B HOCH2CH2OH C HOCH2CH(OH)CH2OH D C2H5OH Cõu 20: Trong phõn t cht hu c X phn trm lng cacbon, hiro ln lt bng 38,71% v 9,68%, li l oxi Khi X tỏc dng vi natri d thu c s mol H2 bng s mol ... thc phõn t ca X l A C2H6O2 B C3H8O2 C C2H2O4 D C4H10O2 Cõu 21 : Ancol no n chc X cú phn trm lng cacbon bng 52,174% t chỏy hon ton m gam hn hp gm X v Y (l ng ng ca X) c 8,96 lớt khớ CO2 (ktc) v...