题干

二氧化硫是造成酸雨的主要物质之一,小丽为探究二氧化硫能与水反应生成酸,设计了如下实验方案.

【查阅资料】石蕊是一种色素,遇到酸变红色,酸是一类物质,能使石蕊变成红色.

【实验设计】她先用紫色石蕊溶液将白色滤纸浸润,干燥后做成紫色的小花,然后按所图所示进行实验.

观察到实验(Ⅰ)和(Ⅲ)中的小花变____色,(Ⅱ)中的小花不变色.

【评价反思】小虎对小丽的实验方案提出了质疑,他认为上述实验还不足以证明“二氧化和水反应生成了酸”,两位同学仔细讨论后认为还需补充如下一个实验,才能得出二氧化硫与水反应生成酸.

实验操作

实验现象

____

____

【拓展应用】二氧化硫也是实验室一种污染气体,实验室做硫在氧气中燃烧的实验时,集气瓶底部放少____,以吸收二氧化硫气体.

上一题 下一题 0.0难度 选择题 更新时间:2016-07-01 04:11:19

答案(点此获取答案解析)

红,将干燥的紫色小花放入二氧化硫气体中,小花不变色,水或碱液

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    Sometimes I have to admire people's imagination but what I admire most is the businessmen's sense of smell. China's Singles Day, which falls on Nov. 11 every year, has far surpassed its U.S. counterparts of Black Friday and Cyber Monday—combined. Last year, Americans spent a record $12.8 billion online between Thanksgiving Day and Cyber Monday. It's impressive until you compare it to the $17.6 billion in sales made by Chinese consumers in a single 24-hour period during 2016's Singles Day.

    Singles Day is known as “Bare Sticks Day” or “Bare Branches Day” in Chinese—because the date “11/11” looks like bare branches and “one” is the loneliest number. Singles Day began in the early 1990s in the dorm rooms of Nanjing University when a group of single friends were sorry about the lack of significant others and decided to mark the day by organizing activities as a group of singles and reducing their loneliness by buying themselves a gift.

    Then in 2009, sensing s break between the sales period of China's National Day on Oct. 1 and Chinese New Year in late January or early February, Alibaba's Jack Ma saw an opening: sell to comfort lonely hearts.

    The first year did only $7.5 million in sales, but just 8 years later, shoppers spent $25.3 billion, or 168.2 billion yuan, this year—a 40 percent jump from last year's $17.6 billion. Foe comparison, Black Friday and Cyber Monday in the U.S. only netted $6.79 billion in 2016. Amazon doesn't release sales figures for July's Prime Day, but it's pretty safe to believe the not-quite-national-holiday doesn't come close to $25 billion.

    “More than $25 billion in one day is not just a sales figure,” Alibaba Group CEO Daniel Zhang said in a statement. “It represents the desire for quality consumption of the Chinese consumer, and it reflects how merchants and consumers alike have now fully accepted the combination of online and offline sales.”