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考点一空气的组成、污染及防治考点分析:空气中氧气含量的测定常以填空题和实验探究题的形式出现,难度较大.空气中各成分的体积分数、空气的污染及防治、纯净物与混合物的区别是中考的热点内容.通常以选择题的形式出现,试题的难度不大.解题指导:测定空气中氧气的体积分数的实验,要联系物理学中的气压知识,要熟知实验原理,分析实验现象,并对实验误差进行分析.例1为测定空气里氧气的含量,甲、乙、三个同学用如图1
Examination of the composition of an air pollution and control test site analysis: Determination of oxygen content in the air often fill in the blank questions and experimental questions in the form of more difficult.Air in the volume fraction of each component, air pollution and control, pure things The difference with the mixture is the hot spot in the exam.Usually in the form of multiple choice questions, the difficulty of the test is not problem solving guidance: the determination of the volume fraction of oxygen in the air experiment, to contact the pressure of physics knowledge, to be familiar with the experiment Principle, analysis of experimental phenomena, and experimental error analysis.Example 1 for the determination of oxygen content in the air, A, B, three classmates as shown in Figure 1