题干

由几种离子化合物组成的混合物,含有以下离子中的若干种:K+、Cl、NH4+、Mg2+、Ba2+、CO32、SO42,将该混合物溶于水后得澄清溶液,现取3份100mL 的该溶液分别进行如下实验:

实验序号

实验内容

实验结果

 ①

加AgNO3溶液

有白色沉淀生成

 ②

加足量NaOH溶液并加热

收集到气体1.12L(标准状况)

 ③

加足量BaCl2溶液时,对所得沉淀进行洗涤、干燥、称量;再向沉淀中加入足量稀盐酸,然后干燥、称量

第一次称量读数为6.27g;第二次称量读数为2.33g

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    Emily was an eighth grader. To pass her Civics course, she had to do some volunteer services in a nursing home for a week.

    One Monday, Emily went to the nursing home after school. When she arrived, she was told she would spend an hour every weekday with an elderly lady, Mrs Blair. She was then led into a room, where an old lady in a flowery dress was sitting on a sofa.

    Emily stood awkwardly(别扭地)in front of the lady. She cleared her throat and said, "Good afternoon. I'm Emily."

    "Good afternoon, Emily. Take a seat, please." Mrs. Blair replied.

    Then,1filled the space between them. Emily wondered what to say.

    "Tell me about yourself, Emily," Mrs Blair said suddenly.

    "Well," Emily started, "I don't have any grandparents, so I don't know how to get on well with elderly people. I love the performing arts. I'm here mainly because I have to volunteer here to get a good grade for my Civics class."

    Mrs Blair didn't seem to mind. 'Many people, especially teens, don't seem to2old people like me. Now you are here, and I'm going to change that about you. Ask me anything."

    Emily thought for a moment, and finally decided, "What was your job?"

    "I was a Broadway star in the 1950s."MrsBlair answered.

    Cool! Can you tell me about it?" Emily asked, amazed.

    Mrs Blair smiled. "Back then3the lead actress had the honor to wear a special bracelet. I was the lead in almost all of the plays, so I always wore the bracelet. Till this day, I still have it."

    Emily smiled along with Mrs Blair and listened to the other stories attentively. She had become very4Mrs Blair's stories. She decided to come earlier the next day.

    Tuesday, Wednesday, and Thursday passed by quickly. Then came Friday. As she was leaving, Emily was really upset to say goodbye.

    "Don't be sad. You can still visit me," Mrs Blair comforted her. She then handed a small box to Emily, "It's my gift to you."

    Emily5opened the box and was surprised to see what was inside. "It's the bracelet that you wore. Thank you!" Emily said, with tears in her eyes free.

    I'm sure to visit you whenever I'm on the way home, Emily thought of her own love for the performing arts. She touched the bracelet and6that she would keep her word to Mrs Blair.