题目

A Little Coaching (指导) I always felt nervous at the running race. I was too thin to be an athlete. So when our class needed a    21     in the two mile race around the lake, I hoped nobody would notice me. I hid under a    22    when our teacher Bronto called the names of the runners. I got more nervous when I heard he called, “Noah! Where’s Noah? He’s in this race!” He saw me under the tree and shouted, “Noah, we    23    a boy to run the two mile race.” He pushed me to the starting line(线). I pleaded(恳求) with him. “I don’t know the way arou某澄清溶液中含有下表离子中的一种或多种。分别取它的水溶液两份进行实验，结果如下：阳离子Fe2+、Fe3+、Al3+阴离子SO32-、CO32-、SiO32-、I－、NO3-①向一份溶液中加入过量盐酸，产生气泡，溶液颜色变深，但仍澄清；②继续向①溶液中加入少许四氯化碳，震荡，静置，下层呈现紫红色，上层溶液呈现黄色；③向另一份溶液中加入过量氢氧化钠溶液，产生沉淀的质量与加入碱液的体积关系如图所示。根据以上信息，回答下列问题：（1）原溶液中肯定含有的离子是______________________________________________；（2）①中生成的气体是______________(填化学符号)，它具有的性质是_____________（填字母序号）；A．无色无味 B．能被NaOH溶液吸收 C．属于大气污染物 D．难溶于水 （3）①中发生反应的离子方程式有_______________________________________________。（4）③中沉淀溶解的化学反应方程式是________________________________________。