问题 问答题

小王同学要想测定二块合金[甲(Cu-Zn)、乙(Cu-Ag)]中铜的质量分数,但实验室只提供一瓶标签模糊的稀盐酸和必要的仪器.根据学过的知识,(1)你认为他能测出铜的质量分数是哪一块合金?是______.(填甲或乙)理由是:______,______.

(2)现小王取该合金粉末32.5g与足量该盐酸充分反应,生成0.2mol氢气,则该合金中铜的质量为______g,该合金中铜的质量分数为______.

答案

(1)甲合金中锌在氢的前面,能与盐酸反应生成氢气,而铜不与盐酸反应生成氢气,乙中的金属都不与盐酸反应生成氢气,所以本题答案为:甲,甲中的锌在氢的前面能与盐酸反应生成氢气,而铜不与盐酸反应生成氢气Zn+2HCl═ZnCl2+H2↑,Cu+HCl不反应

(2)Zn+2HCl═ZnCl2+H2↑,

1                   1

可以看出生成0.2mol氢气需要锌的物质的量为0.2mol,所以锌的质量为0.2mol×65g/mol=13g,所以铜的质量为32.5g-13g=19.5g,

该合金中铜的质量分数为

19.5g
32.5g
×100%=60%,所以本题答案为:19.5,60%.

阅读理解

There are many wetlands(湿地) in China and some of them have become the world‘s important wetlands. The Chinese Yellow Sea Wetlands are among them. They are in Yancheng, Jiangsu Province. They are home for many different kinds of birds and animals. The world’s largest Milu Deer Nature Reserve(自然保护区) is in them. More than 700 milu deer live freely there. There are not many red-crowned cranes in the world, but every winter you can see some in the Red-crowned Cranes Nature Reserve in the Yellow Sea Wetlands.

The temperature in the wetlands is usually neither too high nor too low. There is a lot of rain and sunshine, too. They are really good places for wildlife(野生生物)。 Offering food and home for some special kinds of animals and birds is not the only reason why we need to protect wetlands. Wetlands are important because they also prevent flood. But some people want to change the wetlands to make more space for farms and buildings. This means there will be less and less space for wildlife.

Luckily, more and more people are beginning to realize the important of wetlands and wildlife. Every year, on February 2nd, many activities are held to tell people more about wetlands.

根据以上短文内容,然后从每题所给的四个选项中选择最佳选项。

小题1:The Chinese Yellow Sea Wetlands are in the _______ of China.

A.east

B.south

C.west

D.north小题2:Usually the weather in the wetlands is _______.

A.hot

B.pleasant

C.cold

D.dry小题3:The World Wetlands Day is on _______.

A.April 22

B.June 25

C.February 2

D.March 22小题4:We must protect wetlands because _______.

A.they are home for wildlife

B.they can prevent flood

C.they can offer food to the animals and birds

D.all of the above小题5:The best title for the passage is _______.

A.China‘s Wetlands Have All Entered the World’s List

B.Wetlands—Home for Wildlife and Human Beings

C.Special Animals in the Chinese Yellow Sea Wetlands

D.Wetlands—Valuable Recourses(珍贵资源) of Land on the Earth

问答题 简答题