题目

“I sometimes get up at three or four in the morning and I surf the net．” “I often check my e-mail forty times a day．” “I often spend more than tree hours during one time on the net．” “I spend more time in chat rooms（聊天室）than with my real-life friends．” Do you know any people like these? They are part of a new addiction（瘾）called Internet addiction．Internet addicts spend at least thirty to forty hours online very week．The use of the Internet can be an addiction like drug（毒品） use．People lose contro1（控制） of the time they spend on the In（10分）某无色透明溶液可能含有下列离子：K+、Al3+、Fe3+、Ba2+、NO3－、SO42－、HCO3－、Cl－等，取该溶液进行如下实验：    ①用蓝色石蕊试纸检测该溶液，试纸显红色；    ②取溶液少许，加人铜片和稀硫酸共热，产生无色气体，该气体遇到空气立即变为红棕色；    ③取溶液少许，加人氨水有白色沉淀生成，继续加人过量氨水，沉淀不消失；    ④取溶液少许，滴人氯化钡溶液产生白色沉淀；    ⑤取实验 ④ 后的澄清溶液，滴人硝酸银溶液产生白色沉淀，再加人过量的稀硝酸，沉淀不消失。请回答下列问题：   （1）在实验①中，下图所示的操作中正确的是___________________（填代号）。   （2）根据上述实验判断原溶液中肯定存在的离子是____________________，肯定不存在的离子是_______________。   （3）写出与实验②有关的离子方程式：____________________________。