题目

A young man in his twenties was siting on the train, next to his mother. They both looked tired but excited. The young man was looking out from the window. Suddenly, he shouted, . Mom, the trees are behind us!' 'His voice was so loud that everyone on the train heard him. Mom smiled. But a young couple who were siting nearby looked at the young man with pity- There must be something wrong with his mind, they thought.A few minutes later, the young man shouted again, Mom. the clouds are running with us! Mom smiled again. And she seemed very happy with her son' s words. Finally the couple couldn'（9分） 从C H O S P Na Ca Fe Mn K Cu N等12种元素中选择恰当元素,用离子符号,化学式或化学方程式按下列要求填空:(1). 氢氧根离子______,能使澄清石灰水变浑浊的气体_____,大理石的主要成份＿＿＿＿.(2). 细铁丝在氧气中燃烧__________________(3). 实验室加热紫黑色晶体制取氧气___________________＿＿＿(4). 盐酸与氢氧化钠反应_____________________________________________