2022英语周报七年级29新目标答案

Paragraph 1Several days later, when Jenny's father came in toread her a story, Jenny was waiting anxiously for him on thebed. When listening to the story Jenny was totally absentminded, with her hands holding the necklace tightly andfirmly. When the story came to an end, unexpectedlyJenny offered her beloved necklace to her father, with herfingers trembling automatically. No one knew what thenecklace meant to her. She whispered to her father, softlyand gently, "Daddy, you know I love you more than thenecklace. "Then the necklace slid into her father's handsdeterminedlyParagraph 2Holding the plastic pearl his daughter offered, thefather dragged out a blue box. Much to Jennys amazement, a beautiful real pearl necklace lay peacefully in thebox, which set her heart racing. Jenny froze there,athrilled expression twisting her face. Before Jenny was ableto say something, her father brushed a warm kiss on herface and gathered her into his arms. Holding the genuinenecklace in her hand, Jenny lifted her lip, tears beginningto blur her vision

fC2O3-+14H+6-2Cr++3C2↑+7H2O(2分)(2)制备氯气并探究氯气等物质的相关性质(2分,其他合理答案也给分)作安全瓶,检测实验过程中装置是否堵塞(2分)浓盐酸不能顺利滴入烧瓶(2分)(3)②(1分)(4)实验完毕,打开活塞b,使少量液体流入锥形瓶,关闭活塞,振荡锥形瓶,下层液体呈紫红色(2分)2I+Br2=12+2Br(1分)(5)C、D之间没有干燥管,溴化钠溶液中的水蒸气可能进入U形管使Ⅲ处纸条湿润(或没有排除氯气对溴与KI反应的干扰)(2分)【解析】(1)A中反应的离子方程式为Cr2O+14H++6C1-2Cr3++3Cl2↑+7H2O。(2)本实验的目的是制备氯气并探究氯气等物质的相关性质;装置B的另一个作用是作安全瓶,检测实验过程中装置是否堵塞;若拆去a导管,可能的后果是浓盐酸不能顺利滴入烧瓶。(3)氯化钠不能干燥氯气,碱石灰与氯气反应,不能干燥氯气(4)证明溴的非金属性比碘强的实验操作和现象是实验完毕,打开活塞b,使少量液体流入锥形瓶,关闭活塞,振荡锥形瓶,下层液体呈紫红色,反应的离子方程式为2+Br2=I2+2Br(5)本实验存在的明显不足是C、D之间没有干燥管,溴化钠溶液中的水蒸气可能进入U形管使Ⅲ处纸条湿润或没有排除氯气对溴与KI反应的干扰。

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