问题 填空题

某学校九年级一化学实验小组按如图所示装置测定空气中氧气的含量,燃烧匙内盛有足量的红磷.

(1)点燃后瓶内出现的现象是______

该反应的文字表达式为______

其基本反应类型是______

(2)红磷燃烧完毕后,集气瓶中剩余的气体主要是______

(3)过一会儿,打开弹簧夹又会出现的现象是______

(4)本实验的结论是______.

答案

(1)点燃后瓶内出现的现象是:红磷燃烧发出黄白色火焰,并有大量白烟生成.

产生上述现象的原因是由于磷与氧气在点燃条件下反应生成五氧化二磷.

该反应的文字表达式为:磷+氧气

点燃
五氧化二磷.

该反应由两种物质反应生成一种物质,符合化合反应的概念,属于化合反应.

(2)红磷燃烧完毕后,集气瓶中剩余的气体主要是氮气.

(3)打开弹簧夹后,由于瓶内消耗了氧气,瓶内气压小于外界的大气压,因此烧杯中的水在外界大气压的作用下倒流入集气瓶中,约流入集气瓶容积的

1
5

(4)本实验的结论是:空气主要有氮气和氧气组成,氧气约占空气体积的

1
5

故答案为:

(1)红磷燃烧发出黄白色火焰,并有大量白烟生成;磷+氧气

点燃
五氧化二磷;化合反应.

(2)氮气.

(3)烧杯中的水倒流入集气瓶中,约流入集气瓶容积的

1
5

(4)空气主要有氮气和氧气组成,氧气约占空气体积的

1
5

阅读理解

.

Food is life. It gives us the nourishment we need to stay alive and be healthy. Usually, we eat because we are hungry or need energy. Brian Wansink, a professor at the University of Illinois, says we also eat certain foods because they make us feel good, and remind us of happy memories. Wansink calls this kind of food comfort food. For some people, ice cream is a comfort food. For others, a bowl of noodle soup makes them feel good.

How does a food become comfort food? Professor Wansink believes that we connect food with important times, feelings, and people in our lives. “ When I was a child, my mother made a delicious soup ; I loved it. Now, I often eat this soup when I am tired or worried, and it helps me feel better, ” says one of Wansink’s coworkers.

Do men and women choose different comfort foods? Wansink’s research at the University of Illinois says “yes.” In his study, the favorite comfort food for both men and women was ice cream. After this, men usually preferred hot, savory foods like soup or noodles. Women liked sweet things such as chocolate and cookies. Men and women like to eat comfort foods when they are happy, but women eat these foods more when they are sad or worried.

Not all comfort food is junk (垃圾) food. About 40 percent of the comfort foods in Wansink’s study were healthy main dishes or soups and vegetables. It shows, says Wansink, that a comfort food can taste good and be good for you.

54.The best title for the passage would be         .

A.How to Feel Good                    B.How to Keep Healthy

C.Healthy Foods Make You Feel Good  D.Comfort Foods Make You Feel Good

55.Which of the following is the favorite comfort food for men?

A.soup B.ice cream   C.noodles       D.cookies

56.We can infer from the passage that         .

A.your feeling is connected with what you eat

B.your feeling has nothing to do with what you eat

C.you will feel good if you have noodles

D.you will feel good if you have chocolate

57.The research done by Brian Wansink shows that          .

A.all comfort foods are good for health

B.all comfort foods have bad effects on health

C.women choose the same comfort foods as men

D.women eat more comfort foods when unhappy

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