雷雨天闪电时空气中有臭氧(O3)生成。下列说法正确的是
A．O2和O3互为同位素
B．O2转化为O3为化学变化
C．相同物质的量的O2和O3的体积相同
D．相同质量的O2和O3含有相同的分子数
答案：B
题目分析：A项：O2和O3互为同分异构体，故错；C项：气体所处状况不明，无法判断，故错；D项：O2所含的分子数多，故错。故选B。
点评：本题考查的是氧气和臭氧的相关知识，题目难度不大，学生要平时多注意对基础知识的学习和积累。
| 根据对话内容，从方框内选择合适的句子补全对话。（有两项多余） | |
B: (1) _____ A: My pen pal from Canada hasn't replied to my last two e-mails yet. I don't think she will write to me any more. B: (2) _____ Probably she's busy these days. A: Maybe you're right. (3) _____ B: Why don't you send her an e-card and tell her you miss her very much? A: (4) _____ Thanks for your advice, Bob. B: (5) _____ |