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某矿抽出的废液中含有大量的K+、Cl、Br,还有少量的Ca2+、Mg2+、SO42.某研究性学习小组所拟取这种废液来制取较纯净的氯化钾晶体及液溴(Br2),他们设计了如下流程:

可供试剂a、b的选择试剂:饱和Na2CO3溶液、饱和K2CO3溶液、KOH溶液、BaCl2溶液、Ba(NO32溶液、H2O2、KMnO4(H+)溶液、稀HNO3

请根据以上流程,回答相关问题:

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    Whenever the house gets quiet, Mrs. Smith knows just where to find her 6-year-old daughter Maria: lost in the world of stories.“I like to read every time of the day,” said Maria, a student at Creel Elementary School in Australia.
    Maria's headmaster, Mrs. White, wants each of her 850 students and their families to learn the love of reading this year. She wants reading at home to become an activity of choice in every family, even during holiday breaks. "I truly realize reading should be an important part of everyone’s life, and nothing should stop it." said Mrs. White.
   “The aim we want most of all is to help children understand they can enjoy reading, as well as practice their skills,” said Hannas, an education researcher. He suggested parents take their children to the library and allow them to pick out books that interest them.
    Each night, students take home two books to read with their parents or other family members. They have to return the books the next day with a signed note from their parents showing that the books were read, and have passing tests that check how well they understand the books.
   “We're trying to get parents into the habit of reading with their kids.” said the headmaster. “Nothing is better than sitting on a sofa with your child and reading and laughing.”
    Through books, Mrs. Smith, a parent, said she's able to give her two daughters more experiences than she could.“I think reading opens all the doors and creates imaginations in children,”she said, “I think if you read well, you can succeed in anything in life.”