题目

— I don't know if Tom will attend the party until now.— Really? Tom is eager to do so. A . In the end B . As a matter of fact C . On purpose D . Believe it or not 答案：D物质X在4.8g氧气中恰好完全燃烧，反应方程式为X+3O2RO2+2SO2，测得RO2 和SO2的质量分别为2.2g和6.4g，下列判断中正确的是A．参加反应的X的质量为4.3gB．X的相对分子质量为76C．X中含有R元素、S元素和O元素D．产物为气态时都是空气污染物