问题 问答题

(1)浓硫酸和碳在加热的情况下反应的化学方程式为:______;为了验证反应的各种生成物,用如图Ⅰ装置进行实验.

(2)图Ⅰ中A处是完成实验中的必要装置,它是下列图Ⅱ所示中的(填编号)______;

(3)C装置中应盛的试剂为______,其作用是______;

(4)能够确定存在二氧化碳气体的实验现象是:______.

答案

(1)浓硫酸具有强氧化性能把碳氧化为二氧化碳,本身被还原为二氧化硫,根据题意可知浓硫酸与木炭共热生成CO2、SO2和H2O,

则反应的化学方程式为:C+2H2SO4(浓)

.
CO2↑+2SO2↑+2H2O,故答案为:C+2H2SO4
.
CO2↑+2SO2↑+2H2O;

(2)依次检验CO2、SO2和H2O的存在时,应先检验水蒸气的存在,因为在验证二氧化碳、二氧化硫的存在时都需通过溶液,可带出水蒸气;所以选择无水硫酸铜遇水变蓝验证水的生成,故答案为:③;

(3)二氧化碳、二氧化硫都能使澄清的石灰水变浑浊,所以不能先通过澄清的石灰水来检验二氧化碳的存在,所以先检验二氧化硫的存在并除去二氧化硫后才检验二氧化碳的存在,所以C装置中用高锰酸钾溶液除去二氧化硫,故答案为:酸性高锰酸钾溶液;除去SO2

(4)结合(3)的分析可知能够确定存在二氧化碳气体的实验现象是:C中酸性高锰酸钾溶液不褪色,同时D中澄清石灰水变混浊,

故答案为:C中酸性高锰酸钾溶液不褪色,同时D中澄清石灰水变混浊.

阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

Two brightly colored butterflies have just flown by. They seems to be exactly alike, but actually one is a little larger than the other.   1  The smaller one has a wingspread of less than three inches and also a black line on its back wings.

At first sight, it is hard to tell them apart. Would you guess from this that they are different-sized butterflies of the same species?  2  If you said yes to either question, you would be wrong, for these look-alikes belong to quite different families.

The larger insect is the monarch butterfly (黑脉金斑蝶). As a baby insect, the monarch feeds on milkweed, which seems to give the monarch a disagreeable taste and smell.   3  Birds that eat butterflies soon recognize the monarch and quickly learn to leave it alone.

  4  Birds would find this insect tasty, but because it looks like the monarch, birds keep away from it. The viceroy’s similarity to the monarch gives it some protection from its enemies and helps it survive.

There are other pairs of look-alike butterflies, bees and moths. In each case, one either has a disagreeable taste or smell, or can give a painful sting (叮咬). The larger is called the model.  5  

A.The smaller insect is the viceroy (副王峡蝶), which feeds on the leaves of trees.

B.The larger insect has a wingspread (翼长) of up to four inches.

C.The bright coloring of the monarch acts as a warning sign to its enemy.

D.Birds protect their babies from eating such dangerous enemies.E. The insect that imitates this model for protection is called the mimic(保护色).

F. Or that they are different species of butterflies but close relatives belonging to the same family?

G. Do you like this kind of special species?

单项选择题