一、选择题1.某元素 R 形成的氧化物为 R_2O_3,则 R 的原子结构示意图可能是图1中的( )。2.石油没有同定的沸点,在炼油厂中分馏后能得到汽油、煤油、柴油等产品,由此可以判断石油属于( )。A.单质 B.化合物 C.混合物 D.纯净物3.科学家发现某些元素的原子具有放射性,即原子能自动地放射出一些同定的粒子。据此推断,当一种元素的原子经过放射变化后,结果变成了另一种元素的原子。它一定是放射了 First, the multiple-choice questions 1. R element formed by an oxide of R_2O_3, then the atomic structure of R may be in Figure 1 (). 2. Oil is not the same as the boiling point, after the fractionation in the refinery can get gasoline, kerosene, diesel and other products, which can determine the oil belongs to (). A. Elemental B. Compound C. Mixture D. Purified 3. Scientists have found that the atoms of some elements are radioactive, that is, atomic energy can automatically emit some of the same particles. From this, we can deduce that when an atom of an element undergoes a radioactive change, the result becomes an atom of another element. It must have been radiating