问题 选择题

向含1mol HCl和1mol MgSO4的混合溶液中加入1 mol·L—1Ba(OH)2溶液,产生沉淀的物质的量(n)与加入Ba(OH)2溶液体积(V)间的关系图正确的是  (    )

A.

B.

C.

D.

答案

答案:D

加入氢氧化钡后,立即生成硫酸钡沉淀。当溶液中的氢离子被中和后,再生成氢氧化镁沉淀。中和氯化氢需要0.5L氢氧化钡溶液,当硫酸钡恰好沉淀时,需要1L氢氧化钡溶液,而沉淀镁离子时又需要1L氢氧化钡溶液,因此当沉淀不再变化时,共计需要1.5L氢氧化钡溶液,答案选D。

完形填空

任务型阅读(每小题1分,满分5分)

请认真阅读下面短文,根据短文内容回答短文后的各个问题,并将答案写在每小题下的横线上。

On Sunday, April 22, people all over the world take time out to appreciate(珍惜) the earth that we all share. It’s Earth Day, a special day to learn about our planet(星球) and how to take care of it.

On Earth Day, some people listen to speeches about the environment. Others help clean up their offices or save water and electricity at home. Your parents may even decide to take a day off from driving their cars.

The idea for Earth Day came from a U.S. Senator (参议员), who was worried about the pollution and the health of plants and animals. And the idea quickly caught on. In 1970, the first Earth Day was celebrated. More than 20 million people in cities all over the U.S. took part in. Since then, Earth Day has been used to educate people about their role in taking care of our planet.

Now, Earth Day has become a global celebration. In 1990, 200 million people from 140 countries took part in clean-ups, tree planting and other environmental events on Earth Day.

1. When is Earth Day?

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2. Who came up with the idea for Earth Day?

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3. What does the underlined sentence mean in Chinese?

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4. A lot of people celebrated the first Earth Day in 1970, didn’t they?

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5. What is Earth Day?

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单项选择题