题目

What are the speakers mainly talking about?A.A children’s book. B.A story of a dog. C.An amazing trip. 答案：【答案】B【解析】【原文】W: What are you reading about, Peter?M: A dog named Marvin. In the story, the dog was a writer and he wrote a children’s book titled Marvelous Marvin and visited over 94 hospitals, schools and libraries in three different states.W: That’s just hard to believe!请完成下列填空：（1）在标准状况下，1g 氢气中含有n个氢原子，则阿伏伽德罗常数用n表示为nnmol-1．（2）当SO2和SO3中分子个数比为1：1 时，原子总数之比为3：43：4，分子质量之比为4：54：5．（3）将5mol/L的Mg（NO3）2溶液a mL稀释至b mL，稀释后溶液中NO3-的物质的量浓度是10abmol/L10abmol/L．（4）中和含0.2molHCl的稀盐酸，需NaOH的物质的量为0.2mol0.2mol；如改用KOH，则所需KOH的质量为11.2g11.2g．（5）现有10克由2H和16O组成的水分子，其中含质子数为55mol，中子数为55mol，电子数为55mol．