问题 选择题

下列各种试剂中:①浓溴水②食盐溶液③浓H2SO4④Na2SO3溶液⑤石灰水⑥氢硫酸 ⑦NaClO溶液,长期放置在空气中不容易变质而浓度变小的组合是 ( )

A.①③④

B.④⑤⑥

C.②④⑦

D.只有①③

答案

答案:D

溴单质易挥发,浓度减小。食盐溶液中的水挥发,浓度变大。浓硫酸吸水,浓度减小。亚硫酸钠溶液易被氧化生成硫酸钠而变质。石灰水易吸收空气中的CO2而变质。氢硫酸易被氧化生成硫单质。次氯酸钠易吸收CO2生成次氯酸,次氯酸不稳定,易分解,所以正确的答案是D。

简答题
阅读理解

Mr. King lived with six hundred wild animals on the Greek Island of Kyklos. Ever since he left school, he had traveled all over the word collecting animals for his own zoo. He hoped to collect two examples of every kind of animal on his island. But he was afraid that people would find him someday.

He wrote books about his travels and about his animals that he collected. The money from the books helped to pay for all the food that these animals ate.

One day, when Mr. King was out looking for drinking water, he found oil. He needed money for his travels and for his zoo, and a little oil would buy enough water for what he needed all his life, but he knew that if he told anyone else about it, it would be the end of his zoo and his life’s work. So he decided not to tell anyone else about what he had found, because oil and water couldn’t mix.

小题1:Mr. King traveled all over the world for collecting ______.

A.oil

B.water

C.animals

D.money小题2:What Mr. King needed for his travels and his zoo was_______.

A.water

B.money

C.support

D.friends小题3:Mr. King was afraid that people would find him someday because ________.

A.he hadn’t got enough money for them

B.that would be the end of his zoo

C.he hadn’t got enough water and oil

D.they would buy his animals小题4:Mr. King wrote books to _______.

A.tell people about his story

B.tell people how to find oil

C.get enough money for his animals

D.make money for his travels小题5: In the passage, “oil and water couldn’t mix” means that “_________”.

A.Mr. King needed not only water but also oil

B.oil and water were rather difficult to be mixed together

C.Mr. King’s animals only needed water, not oil

D.if he told the others he found oil, his life’s work would be stopped