问题 选择题

下列除去杂质的实验方法正确的是: 

A.除去CO中少量O2:通过灼热的Cu网后收集气体

B.除去K2CO3固体中少量NaHCO3:置于坩埚中加热

C.用过量氨水除去Al3+溶液中的少量Fe3+

D.除去FeCl3酸性溶液中少量的FeCl2:加入稍过量双氧水后放置

答案

答案:D

A错,氧气与铜反应生成的氧化铜还会与CO气体反应生成铜与二氧化碳气体;

B错,碳酸氢钠受热不稳定分解成碳酸钠、二氧化碳和水,引入新杂质碳酸钠;

C错,铝离子、铁离子均能与过量氨水反应生成沉淀;

D正确;

阅读理解

阅读理解。

     Australia has a lot of lovely animals. The most famous ones are kangaroos and koalas.

     The kangaroo is the symbol of Australia. They have large eyes and ears. They don't walk, they jump.

They use their strong back legs. They can jump at up to 74 kilometers per hour. They can go over nine

meters in one jump!

     Kangaroo mothers have pouches (育儿袋) to carry their babies. The babies stay inside to get milk

and keep warm. Kangaroos are everywhere in Australia. They are on TV, in books and in the shops.

The government even wants to put them on passports (护照).

     There are about 20 to 25 million kangaroos in Australia. That's more than the number of people in

the country! Some kangaroos go hungry because there is not enough to eat. They break into farms for

food. Farmers are very angry with them. To help the farmers, the Australian Government kills some

kangaroos each year.

     The koala is another famous Australian animal. They look like bears, and have small eyes and big

noses. They eat leaves from gum trees, where they spend most of their time.

     Koalas have a special smell. They use it to mark (标识) their home - "this is my place, you can't

come in!"

      Like kangaroos, a koala baby lives in its mother's pouch. But koalas have fewer places to live.

There are about 100,000 koalas in Australia. There is a law to keep them safe.

1. Which animal symbol the Australia?

A. koalas        

B. kangaroos      

C. pandas

2. How many kangaroos in Australia?

A. about 20 to 25 million    

B. about 10 to 25 million  

C. about 20 to 35 million

3. Why does the Australia government kill some kangaroos each year?

A. because there are too many kangaroos.

B. because people don't like kangaroos.

C. because the hungry kangaroos break into farms for food

4. What do koalas mark their homes?

A. gum trees' leaves      

B. a special smell    

C their pouches

5. Which sentences is wrong? 

A. Kangaroos jump high and fast.

B. There is a law to help keep kangaroos safe in Australia.

C. Both kangaroos and koalas have pouches.

选择题