题目

 摩尔质量为Mg·mol-1的气态化合物VL (已换算成标准状况) 溶于mg 水中，得到溶液的溶质质量分数为ω%，物质的量浓度为cmol·L-1，密度为ρg·cm-3，则下列说法正确的是 A. M 可表示为    B. c 可表示为 C. ω%可表示为    D. ρ可表示为 答案：【答案】D 【解析】A、溶液的质量为VM/22.4g；溶液的质量为g，根据质量分数的定义，，解得M=22.4m×ω%/[(1－ω%)V]，故A错误；B、溶质物质的量为V/22.4mol，溶液的体积为，根据c=n/V，则c=1000Vρ/(VM＋22.4m)mol·L－1，故B错误；C、根据A选项分析，故C错误；D、根据c=1000ρω%/M，推出ρ=cM/1000ρω%g/cm3，故D正确。 点睛根据短文内容判断下列说法的正误。My name is Tim．I'm a student in Class Two．Grade Five．I am twelve．Now let me tell you something about my family．My father is a doctor．He is writing an e-mail in the room．My mother is a teacher in a middle school．She is cooking dinner in the kitchen．What am I doing? I am doing my homework．We have a lot of homework to do．After homework，I will play the piano．I like playing the piano very much．（1）Tim is a student in Glass Five，Grade Two．（2）Tim's father is a doctor．He is writing an e-mail．（3）Tim's mother is a teacher．She is washing clothes．（4）Tim is doing his homework．（5）Tim likes playing the piano．