一、表示分子的构成及物质的类别例1(2005年山东省潍坊市)图1是表示气体微粒的示意图,图中“●”和“○”,分别表示不同的原子,其中表示纯净物的是()解析:由纯净物的概念可知,纯净物是由同种分子或同种原子构成的.通过观察题给图示可知,(A)中只含有同一种分子,该分子是由两种不 First, the composition of the molecules and the categories of substances Example 1 (Weifang City, Shandong Province, China) Figure 1 is a schematic diagram showing gas particles. In the figure, “●” and “○” indicate different atoms, respectively, indicating pure substances. Yes () Analysis: According to the concept of pure material, pure material is composed of the same kind of molecules or the same type of atoms. By observing the question to the diagram, we can see that (A) contains only the same kind of molecule, which is composed of two kinds of molecules. Do not