问题 填空题

混合物分离的方法有多种,下列事例中各采取了什么分离方法?

(1)利用过氧化氢溶液和二氧化锰制氧气实验结束后,可采用______的方法或蒸发溶剂的方法将二氧化锰回收利用.

(2)将是有分离成汽油、煤油、柴油、润滑油等可采用______的方法.

(3)工业上采用______或化学方法软化硬水.

答案

(1)反应后达到的是二氧化锰的悬浊液,可利用过滤法或蒸发溶剂法达到二氧化锰.

(2)因为四种物质的沸点不相同,可利用分馏的方法进行逐一分离.

(3)软化硬水主要是减小其中的钙镁离子的浓度,可用蒸馏的方法或采用加化学试剂的方法如石灰纯碱法等.

故答案为:(1)过滤

(2)分馏

(3)蒸馏法

填空题
单项选择题

Government officials reported three new cases of mad cow, bringing the total so far this year to 99. Last year, France recorded just 31 cases of the mad cow disease. The rising numbers are in part (1) a new testing program that focuses on cows that are most (2) . That program has (3) 39 cases. But still 60 new cases were identified in the usual way, (4) were found in 1999. Many scientists (5) that this year, five years after safety precautions were (6) , the number of cases would be (7) .

The rise in cases has (8) some scientists to question whether the disease can be transmitted in ways not yet understood. Scientists are still (9) the disease, first recognized in cows in 1986.

It appears that it is not caused by a bacteria, virus or fungus, but (10) infectious particles called prion, perhaps (11) a virus or other agent. The disease kills cells in the brain, (12) it spongy and full of holes.

France has taken more steps to (13) safety than most European countries, (14) refusing to take English beef (15) the European Union. But some scientists believe that France has not been (16) in imposing the ban on feed that (17) animal pans.

Some French officials hope that the sudden interest in mad cow disease will mean that French consumers will become educated about it, thereby recognizing that French beef is actually (18) controlled. Every cow is given a passport at birth, and extensive information about its parentage and (19) it was raised must be (20) to any slaughterhouse. When a diseased animal is found, the entire herd is destroyed.

8()

A.attempted

B.intended

C.lured

D.prompted