问题 填空题

用分子原子的观点解释下列现象,将解释的要点填写在横线上.

(1)一个水分子的质量约是3×10-26kg,一滴水中大约有1.67×1021个水分子:______.

(2)品红分子在静置的水中扩散______.

(3)6000L氧气能加压装入40L钢瓶中:______.

(4)氧气和液氧都能支持燃烧:______.

(5)过氧化氢分解变成了水和氧气:______.

答案

(1)一个水分子的质量约是3×10-26kg,一滴水中大约有1.67×1021个水分,说明分子的质量和体积都很小.

(2)品红分子在静置的水中扩散,是因为品红分子是在不断的运动的,向四周扩散.

(3)6000L氧气能加压装入40L钢瓶中,是因为分子间有间隔,气体受压后,分子间隔变小,气体的体积减小.氧分子之间有一定的间隔,在加压时分子之间的间隔变小.

(4)氧气和液氧都能支持燃烧,是因为它们是由氧分子构成的,同种物质的分子性质相同.

(5)过氧化氢分解变成了水和氧,是因为过氧化氢分子分裂成了氢原子和氧原子,然后氢原子、氧原子分别重新组合形成水分子、氧分子,大量的水分子、氧分子分别聚集成水、氧气,该事实说明分子是可以再分的.

故答案为:(1)分子的质量和体积都很小;(2)分子是在不断的运动的;(3)分子间有间隔;(4)同种物质的分子性质相同;(5)在化学变化中分子可分,而原子不可分.

判断题
完形填空

PART FOUR WRITING
Section A (10分)
Directions: Read the following passage. Complete the diagram by using the information for the passage.  Write NO MORE THAN THREE WORDS for each answer.
Losing weight is difficult, and keeping it off may be even harder. So Harvard researchers set out to determine exactly how much physical activity women need in midlife to avoid gaining weight as they age.
The researchers found that an hour of moderate activity a day — including such recreational activities as brisk walking, leisurely bicycling, ballroom dancing and playing with children — prevented women of normal weight from gaining more than five pounds over any three-year period. Half that amount of vigorous activity, like running, jogging or fast biking, will do the trick as well, they said.
Women who got the same amount of exercise but were heavier to start with were not able to avoid gaining weight, however. Neither were women of normal weight who got less than seven hours a week of moderate activity, according to the study, published in the March 24 issue of The Journal of the American Medical Association.
The average weight gain over the course of the 15-year study, which followed 34,079 healthy women with an average age of 54 at the beginning, was just over five pounds. The researchers did not take diet into account.
“It’s so hard to lose weight and maintain the loss, so whatever weight you are, you should try to stay that weight — that is a success,” said the paper’s lead author, Dr. I-Min Lee, an associate professor of epidemiology at Harvard School of Public Health.
But any amount of exercise is beneficial, she emphasized. “People shouldn’t just throw up their hands and say, ‘Sixty minutes? I can’t do that,’ and give up. Health is more than weight.”
Title: A research on how to     71   
    72   
To determine how much physical activity women need in midlife to avoid gaining weight as they age
    73    
Research objects
    74    
Types of exercise
Weight gain
Women
75  
An hour of moderate activity a day
● Brisk walking
● Leisurely bicycling
●     76   
● Playing with children
    77   five pounds over a three-year period
Half an hour of
vigorous activity a day
● Running
● Jogging
●     78   
Less than
79   a week of moderate activity
 
Not being avoided
Heavier women
The same as the above
Suggestions
● Staying your weight
●     80