问题 填空题

下列物质都可用于自来水的杀菌消毒.

(1)高铁酸钾(化学式K2FeO4)集氧化、吸附、凝聚、杀菌功能于一体,目前被广泛应用于自来水净化处理领域.高铁酸钾中铁元素的化合价为______.

(2)臭氧(化学式O3)有强氧化性,可用于游泳池、生活用水、污水的杀菌和消毒.臭氧和氧气化学性质不同的原因是______.

(3)漂白粉可用于水的杀菌消毒,其有效成分是次氯酸钙[化学式为Ca(ClO)2].次氯酸钙可发生如下反应:Ca(ClO)2+X+H2O=CaCO3↓+2HClO,则X的化学式为______.

答案

(1)根据化合物中各元素化合价代数和为0,则化合物高铁酸钾K2FeO4中铁元素的化合价=0-(+1)×2-(-2)×4=+6;

(2)对比氧气与臭氧的化学式,氧气分子由2个O原子构成、臭氧分子由3个O原子构成,可知化学性质不同的原因是两种物质分子的构成不同;

(3)反应Ca(ClO)2+X+H2O=CaCO3↓+2HClO中,根据化学变化前后原子种类、个数不变,可判断在物质X的分子中含有1个C原子和2个O原子,则物质X的化学式为CO2

故答案为:

(1)+6;

(2)分子构成不同;

(3)CO2

完形填空
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Celebrating Sleep
World Sleep Day, observed on 21 March, was created to bring attention to the growing number of sleep problems worldwide. Sleep is a natural part of human life, but many people in the modern world ignore its importance. As a result, sleep problems are increasingly common.
In 2002, scientists at the University of Athens in Greece conducted a survey of over 35,000 people in 10 countries around the world, including China, Belgium and South Africa. Of the people that responded to the survey, 24 percent said that they did not sleep well, and based on their responses, 31.6 percent were diagnosed with insomnia and another 17.5 percent were diagnosed with borderline insomnia(失眠). In addition, 30.7 percent of survey respondents reported visiting a doctor for help with sleep problems and 11.6 per cent said that they felt very sleepy during the day.
Overall, the survey found that many people suffer the effects of poor quality sleep, some examples of which are being unable to fall asleep and waking up in the middle of the night. The main factors causing these problems are pressure from school or work and a fast pace of life, but noise pollution and light pollution also interfere with sleep and contribute to poor quality sleep. The survey’s findings are particularly troubling because large numbers of people were found to have difficulty sleeping at night. The short-term effects of this are tiredness and trouble concentrating. If this happens for a long time, the risk of gaining weight and having a heart attack may increase.
There are many things you can do to improve the quality of your sleep. First, you should have regular sleep habits. Try to go to bed and wake up around the same time each day. You also need to make your bedroom a cool, dark, quiet place to sleep so that heat, light and noise do not disturb you. At night, you should also avoid things that contain caffeine, such as chocolate, coffee, tea and many soft drinks, as caffeine may keep you from sleeping.
Getting a good night’s sleep is important for everyone. By following the advice above, you can rest better at night and work better during the day.
Title: Celebrating Sleep
Topic
Context
 
World Sleep Day
Due to __3___of sleep problems, people observed Mar. 21, World Sleep Day, bringing attention to the importance of sleep.
 
Responses of the survey
◆Of 3, 5000 people in 10 countries in the world, there were 24 percent of the people saying they didn’t sleep well.
◆31.6 percent were diagnosed with insomnia and another 17.5 percent were on the  _4___ of sleeplessness.
◆The __5__ of the people feeling sleepy during the day is 11.6.
◆30.7 percent reported__6___ to a doctor for sleep problems.
 
__1___causing sleep problems and their
consequences
◆Under _7____ from school or work, people may have sleep problems.
◆A fast pace of life causes sleep problem as well.
◆Poor quality sleeps also ___8__ from noise or light pollution.
◆There is much __9___ that sleepless people easily gain weight and have a heart attack.
◆Feeling tired and sleepy, people find it hard to concentrate.
___2__ to take to improve sleep quality
◆Have regular sleep habits
◆Make your bedroom cool, dark and quiet
◆Avoid things ___10___caffeine
 
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