题干

实验室制取气体的常见装置如图所示,回答下列问题:

(1)标号a的仪器名称为____ ;

(2)利用AE装置组合制取氧气,反应的化学方程式为____ .实验过程中,发现收集的氧气不纯,可能的原因是____ (写一点),从燃烧条件分析,加热过程中试管内的棉花没有燃烧的原因是____ .

(3)实验室制取二氧化碳的药品为____ (写名称,下同)和____ ,制取二氧化碳的装置组合为 ____ (填标号);该装置还能制取氧气,反应的化学方程式为 ____ .

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\u9525\u5f62\u74f6,2KMnO4=\u25b3K2MnO4+MnO2+O2\u2191,\u672a\u5f85\u5230\u6c14\u6ce1\u8fde

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    People and animals often enjoy loving relationships with each other. When people adopt domesticated (家养的) animals into their families as pets, animals give humans the blessings of companionship and fun in return. In the wild, animals sometimes carry out dramatic rescues of people in dangerous situations, miraculously (奇迹般地) sensing human needs and jumping in without fear to help.

    In 2000, a 6-year-old boy unified Elian Gonzalez left Cuba on a boat bound for Florida in the United States, but the boat sank and everyone aboard drowned except Elian and two adults. Elian and the other two survivors held onto inner tube for 48 hours to try to stay afloat in the sea. After a while, however, Elian began to lose strength, slipping under the water and then grabbing the tube again as he fought to stay alive.

    A small group of dolphins noticed Elian struggling and swan over to him to help. The dolphins formed a circle around the inner tube and took turns using their noses to lift Elian until fishermen working in the area discovered and rescued Elian and the two adults who floated nearby. The fishermen reported that, when they discovered Elian, he was repeating a prayer that his mother had taught him before drowning, asking guardian angels to protect him.

    Miraculously, the dolphins knew that a child would need more help than adults, so they focused on Elian — and they figured out exactly what needed to be done and cooperated to carry out that plan successfully. They made it!