题目

阅读理解.阅读下列短文，根据短文内容，从短文后各题所给的A、B、C、D四个选项中，选择最佳选项。Friendship Restaurant We have different kinds of Japanese food here. The food menu is in Japanese and Chinese. All the waiters or waitresses can speak at least one foreign language. Tel: 312 – 9997 Time: 11:30 am – 10:00 pmVolunteer Project Maybe you want to help others but don’t know how to do it. Then Volunteer Project will help you. Here you will get the best idea of volunteering. Call 822 – 5566 to join it. E-mail: lisa@hotmail.comDream Corner Do you化学兴趣小组的同学在综合实践中了解到，某石灰厂有一批石灰石原料，其中含有的杂质是二氧化硅（二氧化硅不溶于水，不与盐酸反应，高温时不发生分解反应）．为了测定该石灰石的纯度，兴趣小组同学取用2g这种石灰石样品，并取稀盐酸20g分4次加入样品中进行实验，结果如下：稀盐酸的用量/g剩余固体的质量/g第一次加入51.5第二次加入51.0第三次加入50.5第四次加入50.3求：（1）该石灰石样品的纯度是多少？（2）2g此石灰石样品与足量稀盐酸反应最多生成CO2的质量？