1. (2023九上·期末) 一定条件下，下列物质在密闭容器内充分反应，测得反应前后各物质的质量如表所示。下列说法不正确的是（ ）                                                                                                                                                                                

纯净物	C2H5OH	O2	CO2	H2O	X
反应前质量/g	4.6	2.4	0	0	0
反应后质量/g	0	0	2.2	2.7	待测