题干

用高锰酸钾加热制取氧气时.应在试管口塞一小团棉花,其作用是(   )

A:防止试管破裂

B:防止水被吸入试管

C:防止氧气产生太快无法收集

D:防止高锰酸钾粉末进入导管

上一题 下一题 0.0难度 选择题 更新时间:2017-08-01 03:59:17

答案(点此获取答案解析)

D

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    Author Daniel Boorstin suggests that, “Celebrities are people who appear on newspapers, but heroes are people who make history.” If a person is truly a hero, he or she will not be soon forgotten.
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