已知△ABC的两个顶点A，B的坐标分别为（﹣2，0），（2，0），且AC，BC所在直线的斜率之积等于﹣$\frac{1}{4}$．

（1）求顶点C的轨迹方程；

（Ⅱ）若斜率为1的直线l与顶点C的轨迹交于M，N两点，且|MN|=$\frac{8\sqrt{2}}{5}$，求直线l的方程．

点S、A、B、C在半径为 $\sqrt{2}$ 的同一球面上，点S到平面ABC的距离为 $\frac{1}{2}$ ，AB=BC=CA= $\sqrt{3}$ ，则点S与△ABC中心的距离为（   ）

某溶液仅含下列离子中的几种，且所含各种离子的物质的量浓度均为0．lmol/L（忽略水的电离及离子的水解）．K⁺  Ag⁺  Mg²⁺  Al³⁺   NH₄⁺  Cl^﹣  CO₃^2﹣  NO₃^﹣  SO₄^2﹣  I^﹣

用如下各步实验分析该溶液组成：

①取5mL溶液，滴少量稀氨水，发现溶液中有沉淀生成，且离子种类增加．

②用铂丝蘸取溶液，在火焰上灼烧，透过蓝色钻玻璃观察，火焰不显紫色．

③另取溶液加入过量盐酸，有无色气体生成，该无色气体遇空气变成红棕色．

④向步骤③实验所得的溶液中加入BaCl₂溶液，有白色沉淀生成．

请回答下列问题：

（1）由步骤②判断，溶液中一定不含有的阳离子是____ ；步骤③中生成无色气体的化学式是____ 

（2）最终确定溶液中所含阴离子有____ 

（3）另取100mL原溶液，加入足量的NaOH溶液，充分反应后过滤，洗涤，灼烧沉淀至恒重，得到的固体化学式为____ ．

根据短文内容,回答下列问题。
   This is my story. I’m French. I fly planes in Africa.
   One day, when I was flying a very small plane, there was something wrong with the engine(发动机).The engine stopped. The plane was light and I could land it safely on the ground.
   Where was I? I couldn’t see any houses or farms. I had a bottle of water and two oranges. I had a map, too. The first day, I didn’t eat anything. In the evening, I began walking. When the sun went down, the air got cold. Where should I walk? I looked at my map and the moon and the stars. I walked and walked.
   The sun came up on the morning of the second day. It was too hot to walk. In the evening, I began walk. I ate an orange and drank a little water.
   The third day, I ate the second orange. The bottle of water was now empty. There were no houses, no trees, and no water.
   The hot sun came up on the fourth day. Would this be the last day on the earth? I didn’t know. What was that? A bird? A man on a hill? No! Yes, it was! I walked to him excitedly and said hello to him. He looked at me and then gave me some water. I drank and drank...