问题 问答题

A,B,C,D,E,F,G是初中化学常见的物质,其中A,D,G是单质,其它是化合物,C是天然气的主要成分,F的水溶液呈蓝色,G是目前产量最大的金属,图中“-”表示相连的物质两两之间可以发生反应,“→”表示由某一物质可制得另一物质(部分反应物、生成物及反应条件已略去).

(1)物质C的化学式为______.A物质的用途是______(任写一种)

(2)图中涉及复分解反应的化学方程式可能是______

(3)G在D中反应时的现象是______.

答案

(1)C是天然气的主要成分,是甲烷化学式是CH4;甲烷可以制取B,甲烷燃烧生成二氧化碳和水,B又能制取A单质,所以B是水,A是氢气.氢气可以作燃料,可以冶炼金属;

(2)复分解反应是两种化合物相互交换成分生成两种化合物的反应类型,F的水溶液呈蓝色,可以是硫酸铜溶液,G是目前产量最大的金属是铁,E能制取硫酸铜,说明E是铜的化合物,可以是氧化铜,所以氧化铜与硫酸反应生成硫酸铜和水,属于复分解反应,方程式是:CuO+H2SO4═CuSO4+H2O;

(3)G是目前产量最大的金属是铁,D是氧气,铁丝燃烧的现象是剧烈燃烧、火星四射、生成黑色固体,放出热量.

故答案为:(1)CH4;作燃料(或冶炼金属);(2)CuO+H2SO4═CuSO4+H2O;(3)剧烈燃烧、火星四射、生成黑色固体,放出热量.

阅读理解

In many societies, there is often greater acceptance of light skin than dark skin. Light skin may be seen as a mark of beauty, intelligence and success. These beliefs can lead to social pressures even within the same racial or ethnic group, if some members are darker skinned than others.

The result is that skin lightening has become a common activity across Africa, Asia and other areas of the world. More and more people with dark skin are using skin-lightening products, even if it means they may face health risks.

They believe that having whiter skin will improve their lives. Many people think they will have a better chance of getting a job or marrying into a better family. Or they want to look like what their society generally considers beautiful.

Some beauty care products and soaps contain chemicals that make skin lighter. This is also called bleaching. But some of the chemicals are extremely dangerous. One of the most dangerous is hydroquinone(对苯二酚).

Hydroquinone has been banned in several countries. This chemical has been connected to kidney damage and some kinds of cancer. It also causes low birth weight in babies when mothers –to-be use it during pregnancy.

At first, bleaching products make the skin color lighter. But after long-term use they can cause problems. They could even make some skin darker.

The chemicals in the products block and break down the natural process that gives color to skin. The skin loses its natural barrier(障碍)to protect against sunlight. Then the skin can become thick and discolored. Usually the person will use more of the product in an effort to correct the problem, but this only makes it worse.

Fatimata Ly treats skin conditions in the Senegalese capital, Dakar. Doctor Ly says skin bleaching has become a problem throughout Senegal. She says the chemicals are now more dangerous because they are stronger. Some cases have resulted in blackened fingernails, infections and permanent(永久的)skin damage.

And these are not the only risks. Experts say some people who change their skin color suffer emotional damage. They feel regret and sadness. They feel that instead of risking their health, they should have learned to love and accept their skin color as it was.

小题1:What is the text mainly about?

A.The advantages of light skin

B.Introducing skin lightening products

C.The harmfulness of Hydroquinone

D.The health risks of bleaching小题2:What does the underlined word “bleaching” refer to?

A.The process of removing the color

B.The process of making the skin whiter

C.The chemicals that make things white

D.The chemicals that protect skin against sunlight小题3:Why do people want to make their skin lighter?

A.Because they all want to look more beautiful.

B.Because they all want to marry into better families.

C.Because they want to find better jobs.

D.Because they want to improve their lives.小题4:Skin bleaching may cause the problem of ______.

A.emotional problems

B.kidney cancer

C.lighter skin

D.low birth rate小题5:The author holds a/ an ______ attitude towards skin lightening.

A.positive

B.negative

C.supportive

D.optimistic

多项选择题