题目

用正确的化学用语填空： （1）相对分子质量最小的氧化物 ；  （2）保持甲烷化学性质的最小粒子 ； （3）硝酸亚铁溶液中大量存在的阳离子 ； （4）铵根离子 ； （5）图，表示 的原子结构示意图． 答案：分析】（1）相对分子质量为构成分子的各原子的相对原子质量之和；氧化物是只含有两种元素且其中一种元素是氧元素的化合物，相对分子质量最小的氧化物是水． （2）甲烷是由甲烷分子构成的，保持甲烷化学性质的最小粒子是甲烷分子． （3）硝酸亚铁溶液中大量存在的阳离子是亚铁离子，写出其阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空（每空不多于2个单词）。George Stephenson was born in 1781 in a poor family. He had to start work 1.he was only eight.When George was fourteen, he2.（become） his father’s helper. He spent a lot of time 3.（learn） about the engine（发动机）. And on holidays he often took one into pieces and studied each 4.（piece） carefully. Soon he became a very good5.（work）, though（尽管） he could not read 6.write. He began to learn the English letters when he 7.seventeen years old. Every day after he did twelve hours of hard work, he walked a long way to have lessons from a young school teacher. On his eighteenth birthday, he8.（write） his own name for the first time in his life. George invented（发明） many things9.his life. The train was the greatest one of 10.（they）.Today when we watch or take trains from one place to another, we’ll think of this great man—George Stephenson. 1.when 2.became 3.learning 4.piece 5.worker 6.or 7.was 8.wrote 9.in 10.them 【解析】文章介绍了George Stephenson事迹。 1.句意：当他8岁的时候，他不得不开始工作。when 当---时候，引导时间状语从句；根据句意故填when 2.句意...