现有一包氯化钾粉末，可能含有氯化钙、氯化镁、氯化铁、氯化钠等杂质．

【提出问题】如何才能验证氯化钾中所含杂质的成分，并得到纯度较高的氯化钾？

【查阅资料】

①碳酸钾的水溶液显碱性；

②氢氧化钙是微溶物，水中出现过多氢氧化钙就会出现浑浊甚至于沉淀．

【实验方案】

某同学为了验证氯化钾中所含杂质的成分，设计了如下实验方案并进行实验．

①取样品20g放入盛有水的烧杯中，得到无色澄清溶液；

②向①所得溶液中滴加稍过量的氢氧化钾溶液，出现白色浑浊，静止片刻后过滤；

③向②所得的滤液中加入稍过量的碳酸钾溶液，出现白色沉淀，静止片刻后过滤；

④将③所得滤液滴加稍过量的稀盐酸，蒸发结晶．

⑤【交流表达】

Pedro: Hi, Lily. When do you start class in the morning?

Lily: Usually at 8:00.

Pedro: It's early. We start class at 9:00 in Spain.

Lily: When do you usually eat dinner, Pedro?

Pedro: At 9:30 or 10:00 p.m.

Lily: Wow! That's too late. I always go to bed at 9:30. What do you do on the weekend?

Pedro: I often play sports with my friends. Sometimes I go shopping with my mum.

Lily: Sounds interesting. I usually clean my room. Sometimes I cook for my family.

镁带能在二氧化碳中燃烧：2Mg+CO₂2MgO+C  有关说法错误的是（　　）

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