题干

分类和类推是学习和研究化学常用的方法.

(1)在初中化学学习中,我们亲身经历了很多的科学探究活动.若按照是否“用数量表示资料或信息”可将实验分为:定性实验和定量实验.据此可将下列探究活动中的E与①____ (填字母)归为一类,你的依据是②____ .

(2)实验室将无水醋酸钠和碱石灰的固体混合物加强热制甲烷,请根据实验室制取气体的方法推测实验室制取甲烷①____ (填化学式)的发生装置应该同②____ (填字母)一致.

A.实验室用锌和稀硫酸制氢气;B.实验室用氯酸钾和二氧化锰混合加热制氧气.

你确定甲烷发生装置的依据是③____ .

上一题 下一题 0.0难度 选择题 更新时间:2017-05-12 09:43:32

答案(点此获取答案解析)

BC,都是定性实验,CH4,B,反应物是固体,需要加热

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阅读理解

    Deborah Cohen is a senior natural scientist at the Rand Corp and the author of the book A Big Fat Crisis: The Hidden Forces Behind the Obesity Epidemic and How We Can End It. According to the book, there are lots of misunderstandings of obesity.

1).If you're obese, blame your genes.

    Obesity rates have increased. Yet, between 1980 and 2000, the number of Americans who are obese has doubled—too quickly for genetic factors to be responsible.

    At restaurants, a dollar puts more calories on our plates than ever before, because restaurant meals usually have more calories than what we prepare at home, so people who eat out more frequently have higher rates of obesity than those who eat out less.

2).If you're obese, you lack self-control.

    Research shows that if we are faced with too much information, we have a tendency to make poor dietary choices. Our world has become so rich in temptation that we can be led to consume too much in ways we can't understand. Even the most vigilant (警觉的) people may not be up to the task of controlling themselves.

3).Lack of access to fresh fruits and vegetables is responsible for obesity.

    Although the US Department of Agriculture estimates that fewer than 5 percent of Americans live in the “food deserts”, about 65 percent of the nation's population is overweight or obese. For most of us, obesity is not related to access to more fresh fruits and vegetables, but to the choices we make in supermarkets.

4).The problem is not that we eat too much, but that we don't exercise.

    Michelle Obama's “Let's Move” campaign is based on the idea that if kids exercise more, childhood obesity rates will decrease. But there was no significant decrease in physical activity levels as obesity rates climbed in the 1980s and 1990s. In fact, although a drop in work-related physical activity may account for up to 100 fewer calories burned, leisure physical activity appears to have increased. The problem is that we eat too much.