阅读理解，判断对错

      Simon is a good boy. Today is Sunday and it is fine, so Simon's father takes him to visit the Great Wall. The Great Wall is far away from his home. So they are going there by bus. The Great Wall is about six thousand seven hundred kilometres. It's very long and great. Simon is very happy and his father is happy, too.

目前我国统一采用的“北京时间”是哪个时区的时间（    ）

）某废水含有下列离子中的5种（忽略水的电离及离子的水解），K⁺、Cu²⁺、Al³⁺、Fe²⁺、Cl^﹣、CO₃^2﹣、NO₃^﹣、SO₄^2﹣，测得各种离子的物质的量浓度相等．为探究废水的组成，某同学进行了如下实验：

①用铂丝蘸取少量溶液，在火焰上灼烧，透过蓝色钴玻璃观察无紫色火焰．

②另取溶液加入足量稀盐酸，有无色气体生成，该无色气体遇空气变成红棕色，此时溶液依然澄清，且溶液中阴离子种类不变．

③另取溶液加入BaCl₂溶液，有白色沉淀生成．

根据上述实验，以下推测正确的是（　　）