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【单选题】
以下关于化学实验中“先与后”的说法中不正确的是( )A.
使用容量瓶、分液漏斗、滴定管前,先检查是否漏水后洗涤干净
B.
做H 2 还原CuO实验时,先通H 2 后加热CuO;反应完毕后,先撤酒精灯待试管冷却后停止通H 2
C.
点燃可燃性气体如H 2 、CH 4 、C 2 H 4 、C 2 H 2 等时,先检验气体纯度后点燃
D.
用排水法收集气体后,先撤酒精灯后移出导管
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